Active Directory
consists of a series of components that constitute both its logical
structure and its physical structure. It provides a way for
organizations to centrally manage and store their user objects,
computer objects, group membership, and define security boundaries in a logical database structure.
Purpose of Active Directory
Active
Directory stores information about users, computers, and network
resources and makes the resources accessible to users and applications.
It provides a consistent way to name, describe, locate, access, manage,
and secure information about these resources.
Functions of Active Directory
Active Directory provides the following functions:
●Centralizes control of network resources
By centralizing control of resources such as servers, shared files, and printers, only authorized users can access resources in Active Directory.
●Centralizes and decentralizes resource management
Administrators
have Centralized Administration with the ability to delegate
administration of subsets of the network to a limited number of
individuals giving them greater granularity in resource management.
●Store objects securely in a logical structure
Active Directory stores all of the resources as objects in a secure, hierarchical logical structure.
●Optimizes network traffic
The physical structure of Active Directory
enables you to use network bandwidth more efficiently. For example, it
ensures that, when users log on to the network, the authentication
authority that is nearest to the user, authenticates them reducing the
amount of network traffic.
Sites within Active Directory
Sites
are defined as groups of well-connected computers. When you establish
sites, domain controllers within a single site communicate frequently.
This communication minimizes the latency within the site; that is, the time required for a change that is made on one domain controller
to be replicated to other domain controllers. You create sites to
optimize the use of bandwidth between domain controllers that are in
different locations.
Operations Master Roles
When
a change is made to a domain, the change is replicated across all of
the domain controllers in the domain. Some changes, such as those made
to the schema, are replicated across all of the domains in the forest. This replication is called multimaster replication.
During
multimaster replication, a replication conflict can occur if
originating updates are performed concurrently on the same object
attribute on two domain controllers. To avoid replication conflicts,Active Directory uses single master replication, which designates one domain controller as the only domain controller
on which certain directory changes can be made. This way, changes
cannot occur at different places in the network at the same time.Active Directory
uses single master replication for important changes, such as the
addition of a new domain or a change to the forest-wide schema.Operations that use single-master replication are arranged together in specific roles in a forest or domain. These roles are calledoperations master roles. For each operations master role, only the domain controller that holds that role can make the associated directory changes. The domain controller that is responsible for a particular role is called an operations master for that role. Active Directory stores information about which domain controller holds a specific role.
Forest-wide Roles
Forest-wide roles are unique to a forest,forest-wide roles are:
●Schema
masterControls all updates to the schema. The schema contains the
master list of object classes and attributes that are used to create
allActive Directory objects, such as users, computers, and printers.
●Domain naming masterControls the addition or removal of domains in the forest. When you add a new domain to the forest, only the domain controller
that holds the domain naming master role can add the new domain.There
is only one schema master and one domain naming master in the entire
forest.
Domain-wide Roles
Domain-wide roles are unique to each domain in a forest, the domain-wide roles are:
● Primary domain controller emulator (PDC)
Acts
as a Windows NT PDC to support any backup domain controllers (BDCs)
running Microsoft Windows® NT within a mixed-mode domain. This type of
domain has domain controllers that run Windows NT 4.0. The PDC emulator
is the firstdomain controller that you create in a new domain.
● Relative identifier master (RID)
When a new object is created, the domain controller creates a new security principal that represents the object and assigns the object a unique security identifier (SID). This SID consists of a domain SID, which is the same for all security principals created in the domain, and a RID, which is unique for each security principal created in the domain. The RID master allocates blocks of RIDs to each domain controller in the domain. The domain controller then assigns a RID to objects that are created from its allocated block of RIDs.
● Infrastructure master
when
objects are moved from one domain to another, the infrastructure master
updates object references in its domain that point to the object in the
other domain. The object reference contains the object’s globally
unique identifier (GUID), distinguished name, and a SID.Active Directory
periodically updates the distinguished name and the SID on the object
reference to reflect changes made to the actual object, such as moves
within and between domains and the deletion of the object.
The global catalog contains
● The attributes that are most frequently used in queries, such as a user’s first name, last name, and logon name.
● The information that is necessary to determine the location of any object in the directory.
● The
access permissions for each object and attribute that is stored in the
global catalog. If you search for an object that you do not have the
appropriate permissions to view, the object will not appear in the
search results. Access permissions ensure that users can find only
objects to which they have been assigned access.A global catalog server
is adomain controller that, in addition to its full, writable domain
directory partition replica, also stores a partial, read-only replica
of all other domain directory partitionsin the forest . Taking a user
object as an example, it would by default have many different
attributes such as first name, last name, phone number, and many more.
The GC will by default only store the most common of those attributes
that would be used in searchoperations (such as a user’s first and last
names, or login name, for example). The partial attributes that it has
for that object would be enough to allow a search for that object to be
able to locate the full replica of the object inactive directory. This allows searches done against a local GC, and reduces network traffic over the WAN in an attempt to locate objects somewhere else in the network.
Domain Controllers always contain the full attribute list for objects belonging to their domain. If the Domain Controller is also a GC, it will also contain a partial replica of objects from all other domains in the forest.
Active Directory
uses DNS as the name resolution service to identify domains and domain
host computers during processes such as logging on to the network
Similar
to the way a Windows NT 4.0 client will query WINS for a NetBIOS
DOMAIN[1B] record to locate a PDC, or a NetBIOS DOMAIN record for
domain controllers, a Windows 2000, 2003, or Windows XP client can query DNS to find a domain controller by looking for SRV records.
Integration of DNS and Active Directory
The
integration of DNS and Active Directory is essential because a client
computer in a Windows 2000 network must be able to locate a domain
controller so that users can log on to a domain or use the services
that Active Directory provides. Clients locate domain controllers and
services by using A resource records and SRV records. The A resource record contains the FQDN and IP address for the domain controller. TheSRV record contains the FQDN of the domain controller and the name of the service that the domain controller provides.
What Are Active Directory Integrated Zones?
One
benefit of integrating DNS and Active Directory is the ability to
integrate DNS zones into an Active Directory database. A zone is a
portion of the domain namespace that has a logical grouping of resource
records, which allows zone transfers of these records to operate as one
unit.
Active Directory Integrated Zones
Microsoft
DNS servers store information that is used to resolve host names to IP
addresses and IP addresses to host names in a database file that has
the extension .dns
for
each zone.Active Directory integrated zones are primary zones that are
stored as objects in the Active Directory database. If zone objects are
stored in an Active Directory domain partition, they are replicated to
all domain controllers in the domain.
What Are DNS Zones?
A
zone starts as a storage database for a single DNS domain name. If
other domains are added below the domain used to create the zone, these
domains can either be part of the same zone or belong to another zone.
Once a subdomain is added, it can then either be:
●Managed and included as part of the original zone records, or
●Delegated away to another zone created to support the subdomain
Types of Zones
There
are two types of zones, forward lookup and reverse lookup. Forward
lookup zones contain information needed to resolve names within the DNS
domain. They must include SOA and NS records and can include any type
of resource record except the PTR resource record. Reverse lookup zones
contain information needed to perform reverse lookups. They usually
include SOA, NS, PTR, and CNAME records.
With
most queries, the client supplies a name and requests the IP address
that corresponds to that name. This type of query is typically
described as a forward lookup. Active Directory requires forward lookup
zones.
However,
what if a client already has a computer's IP address and wants to
determine the DNS name for the computer? This is important for programs
that implement security based on the connecting FQDN, and is used for
TCP/IP network troubleshooting. The DNS standard provides for this
possibility through reverse lookups.
Once
you have installed Active Directory, you have two options for storing
your zones when operating the DNS server at the new domain controller:
Standard Zone
Zones stored this way are located in .dns text files that are stored in the %SystemRoot%\System32\Dns
folder
on each computer operating a DNS server. Zone file names correspond to
the name you choose for the zone when creating it, such as
Example.microsoft.com.dns if the zone name was example.microsoft.com
This type offers the choice of using either a Standard Primary zone or a Standard Secondary zone.
Standard Primary Zone
For
standard primary-type zones, only a single DNS server can host and load
the master copy of the zone. If you create a zone and keep it as a
standard primary zone, no additional primary servers for the zone are
permitted. Only one server is allowed to accept dynamic updates, also
known as DDNS, and process zone changes. The standard primary model
implies a single point of failure.
Standard Secondary Zone
A
secondary name server gets the data for its zones from another name
server (either a primary name server or another secondary name server)
for that zone across the network. The data in a Secondary zone is Read
only, and updated information must come from additional zone transfers.
The process of obtaining this zone information (i.e., the database
file) across the network is referred to as a zone transfer. Zone
transfers occur over TCP port 53. Secondary servers can provide a means
to offload DNS query traffic in areas of the network where a zone is
heavily queried and used. Additionally, if a primary server is down, a
secondary server can provide some name resolution in the zone until the
primary server is available.
Note: A
Standard Primary zone will not replicate its information to any other
DNS servers, but may allow zone transfers to Secondary zones. Win2003
also supports stub zones. A secondary or stub zone cannot be hosted on
a DNS server that hosts a primary zone for the same domain name.
Directory-integrated Zone
Zones
stored this way are located in the Active Directory tree under the
domain object container. Each directory-integrated zone is stored in a
dnsZone container object identified by the name you choose for the zone
when creating it. Active Directory integrated zones will replicate this
information to other domain controllers in that domain.
Note
If
DNS is running on a Windows 2000 server that is not a domain
controller, it will not be able to use an Active Directory integrated
zones, or replicate with other domain controllers since it does not
have Active Directory installed.
DNS Records
After
you create a zone, additional resource records need to be added to it.
The most common resource records (RRs) to be added are:Table 1. Record
Types
Name Description
Host (A) For mapping a DNS domain name to an IP address used by a computer.
Alias (CNAME) For mapping an alias DNS domain name to another primary or
canonical name.
Mail Exchanger (MX) For mapping a DNS domain, name to the name of a computer that exchange
for forwards mail
Pointer (PTR) For mapping a reverse DNS domain name based on the IP address of a
computer that points to the forward DNS domain name of that computer.
Service location (SRV) For mapping a DNS domain name to a specified list of DNS host computers
that offer a specific type of service, such as Active Directory domain controllers.
Q1. What does the logical component of the Active Directory structure include?
■ Objects:-Resources are stored in the Active Directory as objects.
Sub category:object class
An
object is really just a collection of attributes. A user object, for
example, is made up of attributes such as name, password, phone number,
group membership, and so on. The attributes that make up an object are
defined by an object class. The user class, for example, specifies the
attributes that make up the user object.
The Active Directory Schema:-
The
classes and the attributes that they define are collectively referred
to as the Active Directory Schema—in database terms, a schema is the
structure of the tables and fields and how they are related to one
another. You can think of the Active Directory Schema as a collection
of data (object classes) that defines how the real data of the
directory (the attributes of an object) is organized and stored
■ Domains
The
basic organizational structure of the Windows Server 2003 networking
model is the domain. A domain represents an administrative boundary.
The computers, users, and other objects within a domain share a common
security database.
■ Trees
Multiple
domains are organized into a hierarchical structure called a tree.
Actually, even if you have only one domain in your organization, you
still have a tree. The first domain you create in a tree is called the
root domain. The next domain that you add becomes a child domain of
that root. This expandability of domains makes it possible to have many
domains in a tree. Figure 1-1 shows an example of a tree. Microsoft.com
was the first domain created in Active Directory in this example and is
therefore the root domain.
Figure
1-1 A tree is a hierarchical organization of multiple domains.All
domains in a tree share a common schema and a contiguous namespace. In
the example shown in Figure 1-1, all of the domains in the tree under
the microsoft.com root domain share the namespace microsoft.com. Using
a single tree is fine if your organization is confined within a single
DNS namespace. However, for organizations that use multiple DNS
namespaces, your model must be able to expand outside the boundaries of
a single tree. This is where the forest comes in.
■ Forest
A
forest is a group of one or more domain trees that do not form a
contiguous namespace but may share a common schema and global catalog.
There is always at least one forest on a network, and it is created
when the first Active Directory–enabled computer (domain controller) on
a network is installed.
This
first domain in a forest, called the forest root domain, is special
because it holds the schema and controls domain naming for the entire
forest. It cannot be removed from the forest without removing the
entire forest itself. Also, no other domain can ever be created above
the forest root domain in the forest domain hierarchy.
Figure
1-2 shows an example of a forest with two trees. Each tree in the
forest has its own namespace. In the figure, microsoft.com is one tree
and contoso.com is a second tree. Both are in a forest named
microsoft.com (after the first domain created).
A
forest is the outermost boundary of Active Directory; the directory
cannot be larger than the forest. However, you can create multiple
forests and then create trust relationships between specific domains in
those forests; this would let you grant access to resources and
accounts that are outside of a particular forest.
■Organizational Units
Organizational
Units (OUs) provide a way to create administrative boundaries within a
domain. Primarily, this allows you to delegate administrative tasks
within the domain.OUs serve as containers into which the resources of a
domain can be placed. You can then assign administrative permissions on
the OU itself. Typically, the structure of OUs follows an
organization’s business or functional structure. For example, a
relatively small organization with a single domain might create
separate OUs for departments within the organization.
Q2. What does the physical structure of active directory contain?
Physical structures include domain controllers and sites.
Q3.What is nesting?
The
creation of an OU inside another OU.IMP: - once you go beyond about 12
OUs deep in a nesting structure, you start running into significant
performance issues.
Q4. What is trust relationship and how many types of trust relationship is there in exchange 2003?
Since
domains represent security boundaries, special mechanisms called trust
relationships allow objects in one domain (called the trusted domain)
to access resources in another domain (called the trusting domain).
Windows Server 2003 supports six types of trust relationships:
■ Parent and child trusts
■ Tree-root trusts
■ External trusts
■ Shortcut trusts
■ Realm trusts
■ Forest trusts
Q5. What is a site?
A
Windows Server 2003 site is a group of domain controllers that exist on
one or more IP subnets (see Lesson 3 for more on this) and are
connected by a fast, reliable network connection. Fast means
connections of at least 1Mbps. In other words, a site usually follows
the boundaries of a local area network (LAN). If different LANs on the
network are connected by a wide area network (WAN), you’ll likely
create one site for each LAN.
Q6. What is the use of site?
Sites
are primarily used to control replication traffic. Domain controllers
within a site are pretty much free to replicate changes to the Active
Directory database whenever changes are made. Domain controllers in
different sites compress the replication traffic and operate based on a
defined schedule, both of which are intended to cut down on network
traffic
More specifically, sites are used to control the following:
■ Workstation logon traffic
■ Replication traffic
■ Distributed File System (DFS)
Distributed
File System (DFS) is a server component that provides a unified naming
convention for folders and files stored on different servers on a
network. DFS lets you create a single logical hierarchy for folders and
files that is consistent on a network, regardless of where on the
network those items are actually stored. Files represented in the DFS
might be stored in multiple locations on the network, so it makes sense
that Active Directory should be able to direct users to the closest
physical location of the data they need. To this end, DFS uses site
information to direct a client to the server that is hosting the
requested data within the site. If DFS does not find a copy of the data
within the same site as the client, DFS uses the site information in
Active Directory to determine which file server that has DFS shared
data is closest to the client.
■ File Replication Service (FRS)
Every
domain controller has a built-in collection of folders named SYSVOL
(for System Volume). The SYSVOL folders provide a default Active
Directory location for files that must be replicated throughout a
domain. You can use SYSVOL to replicate Group Policy Objects, startup
and shutdown scripts, and logon and logoff scripts. A Windows Server
2003 service named File Replication Service (FRS) is responsible for
replicating files in the SYSVOL folders between domain controllers. FRS
uses site boundaries to govern the replication of items in the SYSVOL
folders.
Q7. What are the objects a site contains?
Sites
contain only two types of objects. The first type is the domain
controllers contained in the site. The second type of object is the
site links configured to connect the site to other sites.
Q8.What is a Site link?
Within
a site, replication happens automatically. For replication to occur
between sites, you must establish a link between the sites. There are
two components to this link: the actual physical connection between the
sites (usually a WAN link) and a site link object. The site link object
is created within Active Directory and determines the protocol used for
transferring replication traffic (Internet Protocol [IP] or Simple Mail
Transfer Protocol [SMTP]). The site link object also governs when
replication is scheduled to occur.
Q9. Explain Replication in Active directory?
Windows
Server 2003 uses a replication model called multimaster replication, in
which all replicas of the Active Directory database are considered
equal masters. You can make changes to the database on any domain
controller and the changes will be replicated to other domain
controllers in the domain.Domain controllers in the same site replicate
on the basis of notification. When changes are made on a domain
controller, it notifies its replication partners (the other domain
controllers in the site); the partners then request the changes and
replication occurs. Because of the high-speed, low-cost connections
assumed within a site, replication occurs as needed rather than
according to a schedule.You should create additional sites when you
need to control how replication traffic occurs over slower WAN links.
For example, suppose you have a number of domain controllers on your
main LAN and a few domain controllers on a LAN at a branch location.
Those two LANs are connected to one another with a slow (256K) WAN
link. You would want replication traffic to occur as needed between the
domain controllers on each LAN, but you would want to control traffic
across the WAN link to prevent it from affecting higher priority
network traffic. To address this situation, you would set up two sites—
one site that contained all the domain controllers on the main LAN and
one site that contained all the domain controllers on the remote LAN.
Q10. What are the different types of replication?
Single site (called intrasite replication)
Replication between sites (called intersite replication)
■ Intrasite Replication
Intrasite
replication sends replication traffic in an uncompressed format. This
is because of the assumption that all domain controllers within the
site are connected by high-bandwidth links. Not only is the traffic
uncompressed, but replication occurs according to a change notification
mechanism. This means that if changes are made in the domain, those
changes are quickly replicated to the other domain controllers.
■ Intersite Replication
Intersite
replication sends all data compressed. This shows an appreciation for
the fact that the traffic will probably be going across slower WAN
links (as opposed to the LAN connectivity intrasite replication
assumes), but it increases the server load because
compression/decompression is added to the processing requirements. In
addition to the compression, the replication can be scheduled for times
that are more appropriate to your organization. For example, you may
decide to allow replication only during slower times of the day. Of
course, this delay in replication (based on the schedule) can cause
inconsistency between servers in different sites.
Q11. What is LDAP?
LDAP,
Lightweight Directory Access Protocol, is an Internet protocol that
email and other programs use to look up information from a server.An
LDAP-aware directory service (such as Active Directory) indexes all the
attributes of all the objects stored in the directory and publishes
them. LDAP-aware clients can query the server in a wide variety of ways.
Q12.What types of naming convention active directory uses?
Active
Directory supports several types of names for the different formats
that can accessActive Directory.These names include:■ Relative
Distinguished NamesThe relative distinguished name (RDN) of an object
identifies an object uniquely, but only within its parent container.
Thus the name uniquely identifies the object relative to the other
objects within the same container. In the example
CN=wjglenn,CN=Users,DC=contoso,DC=com, the relative distinguished name
of the object is CN=wjglenn. The relative distinguished name of the
parent organizational unit is Users. For most objects, the relative
distinguished name of an object is the same as that object’s Common
Name attribute. Active Directory creates the relative distinguished
name automatically, based on information provided when the object is
created. Active Directory does not allow two objects with the same
relative distinguished name to exist in the same parent container.The
notations used in the relative distinguished name (and in the
distinguished name discussed in the next section) use special notations
called LDAP attribute tags to identify each part of the name. The three
attribute tags used include:
■ DC
The Domain Component (DC) tag identifies part of the DNS name of the domain, such as COM or ORG.
■ OU
The Organizational Unit (OU) tag identifies an organizational unit container.
■ CN
The Common Name (CN) tag identifies the common name configured for an Active Directory object.
■ Distinguished Names
Each
object in the directory has a distinguished name (DN) that is globally
unique and identifies not only the object itself, but also where the
object resides in the overall object hierarchy. You can think of the
distinguished name as the relative distinguished name of an object
concatenated with the relative distinguished names of all parent
containers that make up the path to the object.An example of a typical
distinguished name would be:CN=wjglenn,CN=Users,DC=contoso,DC=com.This
distinguished name would indicate that the user object wjglenn is in
the Users container, which in turn is located in the contoso.com
domain. If the wjglenn object is moved to another container, its DN
will change to reflect its new position in the hierarchy. Distinguished
names are guaranteed to be unique in the forest, similar to the way
that a fully qualified domain name uniquely identifies an object’s
placement in a DNS hierarchy. You cannot have two objects with the same
distinguished name.
■ User Principal Names
The
user principal name that is generated for each object is in the form
username@ domain_name. Users can log on with their user principal name,
and an administrator can define suffixes for user principal names if
desired. User principal names should be unique, but Active Directory
does not enforce this requirement. It’s best, however, to formulate a
naming convention that avoids duplicate user principal names.
■ Canonical Names
An
object’s canonical name is used in much the same way as the
distinguished name— it just uses a different syntax. The same
distinguished name presented in the preceding section would have the
canonical name:contoso.com/Users/wjglenn.As you can see, there are two
primary differences in the syntax of distinguished names and canonical
names. The first difference is that the canonical name presents the
root of the path first and works downward toward the object name. The
second difference is that the canonical name does not use the LDAP
attribute tags (e.g., CN and DC).
Q13. What is multimaster replication?
Active
Directory follows the multimaster replication which every replica of
the Active Directory partition held on every domain is considered an
equal master. Updates can be made to objects on any domain controller,
and those updates are then replicated to other domain controllers.
Q14.Which two operations master roles should be available when new security principals are being created and named?
Domain naming master and the relative ID master
Q15. What are different types of groups?
■ Security groups
Security
groups are used to group domain users into a single administrative
unit. Security groups can be assigned permissions and can also be used
as e-mail distribution lists. Users placed into a group inherit the
permissions assigned to the group for as long as they remain members of
that group. Windows itself uses only security groups.
■ Distribution groups
These
are used for nonsecurity purposes by applications other than Windows.
One of the primary uses is within an e-mailAs with user accounts, there
are both local and domain-level groups. Local groups are stored in a
local computer’s security database and are intended to control resource
access on that computer. Domain groups are stored in Active Directory
and let you gather users and control resource access in a domain and on
domain controllers.
Q16. What is a group scope and what are the different types of group scopes?
Group
scopes determine where in the Active Directory forest a group is
accessible and what objects can be placed into the group. Windows
Server 2003 includes three group scopes: global, domain local, and
universal.
■ Global groups
are
used to gather users that have similar permissions requirements. Global
groups have the following characteristics:1. Global groups can contain
user and computer accounts only from the domain in which the global
group is created.2. When the domain functional level is set to Windows
2000 native or Windows Server 2003 (i.e., the domain contains only
Windows 2000 or 2003 servers), global groups can also contain other
global groups from the local domain.3. Global groups can be assigned
permissions or be added to local groups in any domain in a forest.
■ Domain local groups
exist
on domain controllers and are used to control access to resources
located on domain controllers in the local domain (for member servers
and workstations, you use local groups on those systems instead).
Domain local groups share the following characteristics:1. Domain local
groups can contain users and global groups from any domain in a forest
no matter what functional level is enabled.2. When the domain
functional level is set to Windows 2000 native or Windows Server 2003,
domain local groups can also contain other domain local groups and
universal groups.
■ Universal groups
are
normally used to assign permissions to related resources in multiple
domains. Universal groups share the following characteristics:
1. Universal groups are available only when the forest functional level is set to Windows 2000 native or Windows Server 2003.
2. Universal groups exist outside the boundaries of any particular domain and are managed by Global Catalog servers.
3. Universal groups are used to assign permissions to related resources in multiple domains.
4. Universal groups can contain users, global groups, and other universal groups from any domain in a forest.
5. You can grant permissions for a universal group to any resource in any domain.
Q17. What are the items that groups of different scopes can contain in mixed and native mode domains?
Q18. What is group nesting?
Placing
of one group in another is called as group nestingFor example, suppose
you had juniorlevel administrators in four different geographic
locations, as shown in Figure 4-10. You could create a separate group
for each location (named something like Dallas JuniorAdmins). Then, you
could create a single group named Junior Admins and make each of the
location-based groups a member of the main group. This approach would
allow you to set permissions on a single group and have those
permissions flow down to the members, yet still be able to subdivide
the junior administrators by location.
Q19. How many characters does a group name contain?
64
Q20. Is site part of the Active Directory namespace?
NO:
- When a user browses the logical namespace, computers and users are
grouped into domains and OUs without reference to sites. However, site
names are used in the Domain Name System (DNS) records, so sites must
be given valid DNS names.
Q21. What is DFS?
The
Distributed File System is used to build a hierarchical view of
multiple file servers and shares on the network. Instead of having to
think of a specific machine name for each set of files, the user will
only have to remember one name; which will be the 'key' to a list of
shares found on multiple servers on the network. Think of it as the
home of all file shares with links that point to one or more servers
that actually host those shares.DFS has the capability of routing a
client to the closest available file server by using Active Directory
site metrics. It can also be installed on a cluster for even better
performance and reliability.
Understanding the DFS Terminology
It is important to understand the new concepts that are part of DFS. Below is an definition of each of them.
Dfs root:
You can think of this as a share that is visible on the network, and in this share you can have additional files and folders.
Dfs link:
A
link is another share somewhere on the network that goes under the
root. When a user opens this link they will be redirected to a shared
folder.
Dfs target (or replica):
This
can be referred to as either a root or a link. If you have two
identical shares, normally stored on different servers, you can group
them together as Dfs Targets under the same link.
Windows
2003 offers a revamped version of the Distributed File System found in
Windows 2000, which has been improved to better performance and add
additional fault tolerance, load balancing and reduced use of network
bandwidth. It also comes with a powerful set of command-line scripting
tools which can be used to make administrative backup and restoration
tasks of the DFS namespaces easier. The client windows operating system
consists of a DFS client which provides additional features as well as
caching.
Q22. What are the types of replication in DFS?
There
are two types of replication: * Automatic - which is only available for
Domain DFS * Manual - which is available for stand alone, DFS and
requires all files to be replicated manually.
Q23. Which service is responsible for replicating files in SYSVOL folder?
File Replication Service (FRS)
Q24. What all can a site topology owner do?
The
site topology owner is the name given to the administrator (or
administrators) that oversee the sitetopology. The owner is responsible
for making any necessary changes to the site as the physical network
grows and changes. The site topology owner’s responsibilities include:■
Making changes to the site topology based on changes to the physical
network topology.■ Tracking subnetting information for the network.
This includes IP addresses, subnet masks, and the locations of the
subnets.■ Monitoring network connectivity and setting the costs for
links between sites.
Q1. What is DNS.
DNS
provides name registration and name to address resolution capabilities.
And DNS drastically lowers the need to remember numeric IP addresses
when accessing hosts on the Internet or any other TCP/IP-based
network.Before DNS, the practice of mapping friendly host or computer
names to IP addresses was handled via host files. Host files are easy
to understand. These are static ASCII text files that simply map a host
name to an IP address in a table-like format. Windows ships with a
HOSTS file in the \winnt\system32\drivers\etc subdirectoryThe
fundamental problem with the host files was that these files were labor
intensive. A host file is manually modified, and it is typically
centrally administrated.The DNS system consists of three components:
DNS data (called resource records), servers (called name servers), and
Internet protocols for fetching data from the servers.
Q2. Which are the four generally accepted naming conventions?
NetBIOS Name (for instance, SPRINGERS01)
TCP/IP Address (121.133.2.44)
Host Name (Abbey)
Media Access Control (MAC) —this is the network adapter hardware address
Q3. How DNS really works?
DNS
uses a client/server model in which the DNS server maintains a static
database of domain names mapped to IP addresses. The DNS client, known
as the resolver, perform queries against the DNS servers. The bottom
line? DNS resolves domain names to IP address using these steps
Step 1.
A client (or “resolver”) passes its request to its local name server.
For example, the URL term www.idgbooks.com typed into Internet Explorer
is passed to the DNS server identified in the client TCP/IP
configuration. This DNS server is known as the local name server.
Step 2.
If, as often happens, the local name server is unable to resolve the
request, other name servers are queried so that the resolver may be
satisfied.
Step 3.
If all else fails, the request is passed to more and more, higher-level
name servers until the query resolution process starts with far-right
term (for instance, com) or at the top of the DNS tree with root name
servers
Q4. Which are the major records in DNS?
1. Host or Address Records (A):-
map
the name of a machine to its numeric IP address. In clearer terms, this
record states the hostname and IP address of a certain machine. Have
three fields: Host Name, Domain, Host IP Address.
E.g.:- eric.foobarbaz.com. IN A 36.36.1.6
It
is possible to map more than one IP address to a given hostname. This
often happens for people who run a firewall and have two 19thernet
cards in one machine. All you must do is add a second A record, with
every column the same save for the IP address.
2. Aliases or Canonical Name Records (CNAME)
“CNAME”
records simply allow a machine to be known by more than one hostname.
There must always be an A record for the machine before aliases can be
added. The host name of a machine that is stated in an A record is
called the canonical, or official name of the machine. Other records
should point to the canonical name. Here is an example of a
CNAME:www.foobarbaz.com. IN CNAME eric.foobarbaz.com.You can see the
similarities to the previous record. Records always read from left to
right, with the subject to be queried about on the left and the answer
to the query on the right. A machine can have an unlimited number of
CNAME aliases. A new record must be entered for each alias.You can add
A or CNAME records for the service name pointing to the machines you
want to load balance.
3. Mail Exchange Records (MX)
MX”
records are far more important than they sound. They allow all mail for
a domain to be routed to one host. This is exceedingly useful – it
abates the load on your internal hosts since they do not have to route
incoming mail, and it allows your mail to be sent to any address in
your domain even if that particular address does not have a computer
associated with it. For example, we have a mail server running on the
fictitious machine eric.foobarbaz.com. For convenience sake, however,
we want our email address to be “user@foobarbaz.com” rather than
“user@eric.foobarbaz.com”. This is accomplished by the record shown
below:
foobarbaz.com. IN MX 10 eric.foobarbaz.com.
The
column on the far left signifies the address that you want to use as an
Internet email address. The next two entries have been explained
thoroughly in previous records. The next column, the number “10”, is
different from the normal DNS record format. It is a signifier of
priority. Often larger systems will have backup mail servers, perhaps
more than one. Obviously, you will only want the backups receiving mail
if something goes wrong with the primary mail server. You can indicate
this with your MX records. A lower number in an MX record means a
higher priority, and mail will be sent to the server with the lowest
number (the lowest possible being 0). If something happens so that this
server becomes unreachable, the computer delivering the mail will
attempt every other server listed in the DNS tables, in order of
priority.
Obviously,
you can have as many MX records as you would like. It is also a good
idea to include an MX record even if you are having mail sent directly
to a machine with an A record. Some sendmail programs only look for MX
records.
It
is also possible to include wildcards in MX records. If you have a
domain where your users each have their own machine running mail
clients on them, mail could be sent directly to each machine. Rather
than clutter your DNS entry, you can add an MX record like this one:
*.foobarbaz.com. IN MX 10 eric.foobarbaz.com.
This would make any mail set to any individual workstation in the foobarbaz.com domain go through the server eric.foobarbaz.com.
One should use caution with wildcards; specific records will be given precedence over ones containing wildcards.
4. Pointer Records (PTR)
Although
there are different ways to set up PTR records, we will be explaining
only the most frequently used method, called
“in-addr.arpa”.In-addr.arpa PTR records are the exact inverse of A
records. They allow your machine to be recognized by its IP address.
Resolving a machine in this fashion is called a “reverse lookup”. It is
becoming more and more common that a machine will do a reverse lookup
on your machine before allowing you to access a service (such as a
World Wide Web page). Reverse lookups are a good security measure,
verifying that your machine is exactly who it claims to be.
In-addr.arpa records look as such:6.1.36.36.in-addr.arpa. IN PTR
eric.foobarbaz.com.As you can see from the example for the A record in
the beginning of this document, the record simply has the IP address in
reverse for the host name in the last column.A note for those who run
their own name servers: although Allegiance Internet is capable of
pulling zones from your name server, we cannot pull the inverse zones
(these in-addr.arpa records) unless you have been assigned a full class
C network. If you would like us to put PTR records in our name servers
for you, you will have to fill out the online web form on the
support.allegianceinternet.com page.
5. Name Server Records (NS)
NS
records are imperative to functioning DNS entries. They are very
simple; they merely state the authoritative name servers for the given
domain. There must be at least two NS records in every DNS entry. NS
records look like this:foobarbaz.com. IN NS draven.foobarbaz.com.There
also must be an A record in your DNS for each machine you enter as A
NAME server in your domain.If Allegiance Internet is doing primary and
secondary names service, we will set up these records for you
automatically, with “nse.algx.net” and “nsf.algx.net” as your two
authoritative name servers.
6. Start Of Authority Records (SOA)
The
“SOA” record is the most crucial record in a DNS entry. It conveys more
information than all the other records combined. This record is called
the start of authority because it denotes the DNS entry as the official
source of information for its domain. Here is an example of a SOA
record, then each part of it will be explained:foobarbaz.com. IN SOA
draven.foobarbaz.com. hostmaster.foobarbaz.com. (
1996111901 ; Serial
10800 ; Refresh
3600 ;Retry
3600000 ; Expire
86400 ) ; Minimum
The
first column contains the domain for which this record begins authority
for. The next two entries should look familiar. The
“draven.foobarbaz.com” entry is the primary name server for the domain.
The last entry on this row is actually an email address, if you
substituted a “@” for the first “.”. There should always be a viable
contact address in the SOA record.
The
next entries are a little more unusual then what we have become used
to. The serial number is a record of how often this DNS entry has been
updated. Every time a change is made to the entry, the serial number
must be incremented. Other name servers that pull information for a
zone from the primary only pull the zone if the serial number on the
primary name server’s entry is higher than the serial number on it’s
entry. In this way the name servers for a domain are able to update
themselves. A recommended way of using your serial number is the
YYYYMMDDNN format shown above, where the NN is the number of times that
day the DNS has been changed.
Also,
a note for Allegiance Internet customers who run their own name
servers: even if the serial number is incremented, you should still
fill out the web form and use the comment box when you make changes
asking us to pull the new zones.
All
the rest of the numbers in the record are measurements of time, in
seconds. The “refresh” number stands for how often secondary name
servers should check the primary for a change in the serial number.
“Retry” is how long a secondary server should wait before trying to
reconnect to primary server if the connection was refused. “Expire” is
how long the secondary server should use its current entry if it is
unable to perform a refresh, and “minimum” is how long other name
servers should cache, or save, this entry.
There
can only be one SOA record per domain. Like NS records, Allegiance
Internet sets up this record for you if you are not running your own
name server.
Quick Summary of the major records in DNS
Q5.What is a DNS zone?
A
zone is simply a contiguous section of the DNS namespace. Records for a
zone are stored and managed together. Often, subdomains are split into
several zones to make manageability easier. For example,
support.microsoft.com and msdn.microsoft.com are separate zones, where
support and msdn are subdomains within the Microsoft.com domain.
Q6. Name the two Zones in DNS?
DNS
servers can contain primary and secondary zones. A primary zone is a
copy of a zone where updates can be made, while a secondary zone is a
copy of a primary zone. For fault tolerance purposes and load
balancing, a domain may have several DNS servers that respond to
requests for the same information.The entries within a zone give the
DNS server the information it needs to satisfy requests from other computersor DNS servers.
Q7. How many SOA record does each zone contain?
Each
zone will have one SOA record. This records contains many miscellaneous
settings for the zone, such as who is responsible for the zone, refresh
interval settings, TTL (Time To Live) settings, and a serial number
(incremented with every update).
Q8. Short summary of the records in DNS?
The
NS records are used to point to additional DNS servers. The PTR record
is used for reverse lookups (IP to name). CNAME records are used to
give a host multiple names. MX records are used when configuring a
domain for email.
Q9. What is an AD-integrated zone?
AD-integrated
zones store the zone data in Active Directory and use the same
replication process used to replicate other data between domain
controllers. The one catch with AD-integrated zones is that the DNS
server must also be a domain controller. Overloading DNS server
responsibilities on your domain controllers may not be something you
want to do if you plan on supporting a large volume of DNS requests.
Q10.What is a STUB zone?
A
stub zone is a copy of a zone that contains only those resource records
necessary to identify the authoritative Domain Name System (DNS)
servers for that zone. A stub zone is used to resolve names between
separate DNS namespaces. This type of resolution may be necessary when
a corporate merger requires that the DNS servers for two separate DNS
namespaces resolve names for clients in both namespaces.The master
servers for a stub zone are one or more DNS servers authoritative for
the child zone, usually the DNS server hosting the primary zone for the
delegated domain name.
Q11. What does a stub zone consists of?
A
stub zone consists of:•The start of authority (SOA) resource record,
name server (NS) resource records, and the glue A resource records for
the delegated zone.•The IP address of one or more master servers that
can be used to update the stub zone.
Q12. How the resolution in a stub zone takes place?
When
a DNS client performs a recursive query operation on a DNS server
hosting a stub zone, the DNS server uses the resource records in the
stub zone to resolve the query. The DNS server sends an iterative query
to the authoritative DNS servers specified in the NS resource records
of the stub zone as if it were using NS resource records in its cache.
If the DNS server cannot find the authoritative DNS servers in its stub
zone, the DNS server hosting the stub zone attempts standard recursion
using its root hints.The DNS server will store the resource records it
receives from the authoritative DNS servers listed in a stub zone in
its cache, but it will not store these resource records in the stub
zone itself; only the SOA, NS, and glue A resource records returned in
response to the query are stored in the stub zone. The resource records
stored in the cache are cached according to the Time-to-Live (TTL)
value in each resource record. The SOA, NS, and glue A resource records,
which
are not written to cache, expire according to the expire interval
specified in the stub zone's SOA record, which is created during the
creation of the stub zone and updated during transfers to the stub zone
from the original, primary zone.If the query was an iterative query,
the DNS server returns a referral containing the servers specified in
the stub zone.
Q 13.What is the benefits of Active Directory Integration?
For
networks deploying DNS to support Active Directory,
directory-integrated primary zones are strongly recommended and provide
the following benefits:
- Multimaster update and enhanced security based on the capabilities of Active Directory
In
a standard zone storage model, DNS updates are conducted based upon a
single-master update model. In this model, a single authoritative DNS
server for a zone is designated as the primary source for the zone.
This
server maintains the master copy of the zone in a local file. With this
model, the primary server for the zone represents a single fixed point
of failure. If this server is not available, update requests from DNS
clients are not processed for the zone.
With directory-integrated storage, dynamic updates to DNS are conducted based upon a multimaster update model.
In
this model, any authoritative DNS server, such as a domain controller
running a DNS server, is designated as a primary source for the zone.
Because the master copy of the zone is maintained in the Active
Directory database, which is fully replicated to all domain
controllers, the zone can be updated by the DNS servers operating at
any domain controller for the domain.
With
the multimaster update model of Active Directory, any of the primary
servers for the directory-integrated zone can process requests from DNS
clients to update the zone as long as a domain controller is available
and reachable on the network.
Also,
when using directory-integrated zones, you can use access control list
(ACL) editing to secure a dnsZone object container in the directory
tree. This feature provides granulated access to either the zone or a
specified RR in the zone.
For
example, an ACL for a zone RR can be restricted so that dynamic updates
are only allowed for a specified client computer or a secure group such
as a domain administrators group. This security feature is not
available with standard primary zones.
Note
that when you change the zone type to be directory-integrated, the
default for updating the zone changes to allow only secure updates.
Also, while you may use ACLs on DNS-related Active Directory objects,
ACLs may only be applied to the DNS client service.
- Directory replication is faster and more efficient than standard DNS replication.
Because
Active Directory replication processing is performed on a per-property
basis, only relevant changes are propagated. This allows less data to
be used and submitted in updates for directory-stored zones.
Note:
Only primary zones can be stored in the directory. A DNS server cannot
store secondary zones in the directory. It must store them in standard
text files. The multimaster replication model of Active Directory
removes the need for secondary zones when all zones are stored in
Active Directory.
Q14. What is Scavenging?
DNS
scavenging is the process whereby resource records are automatically
removed if they are not updated after a period of time. Typically, this
applies to only resource records that were added via DDNS, but you can
also scavenge manually added, also referred to as static, records. DNS
scavenging is a recommended practice so that your DNS zones are
automatically kept clean of stale resource records
.
Q15. What is the default interval when DNS server will kick off the scavenging process?
The default value is 168 hours, which is equivalent to 7 days.
DNS Q&A
Q1. How do I use a load balancer with my name servers?
Just wanted to ask a question about load balanced DNS servers
> via an external network load balancing appliance (i.e - F5's Big IP,
> Cisco's Content Switches/ Local Directors).
> The main question being the configuration whether to use 2
> Master/Primary Servers or is it wiser to use 1 Primary and 1
> Secondary? The reason is that I feel there are two configurations
> that could be setup. One in which only the resolvers query the
> virtual IP address on the load balancing appliance or actually
> configure your NS records to point to the Virtual Address so that all
> queries, ie - both by local queries directly from local users and
> also queries from external DNS servers. I've included a text
> representation of the physical configuration. Have you ever
> heard or architected such a configuration?
> VIP = 167.147.1.5
> ------------------------------------
>> Load Balancer Device |
> ------------------------------------
> |
> |
> -----------------
> | |
> ---------------- --------------
>> DNS 1 | | DNS 2 |
> ---------------- --------------
> 1.1.1.1 1.1.1.2
There's
usually not much need to design solutions like these, since most name
server implementations will automatically choose the name server that
responds most quickly. In other words, if DNS 1 fails, remote name
servers will automatically try DNS 2, and vice versa.
However,
it can be useful for resolvers. In that case, you don't need to worry
about NS records (since resolvers don't use them), just setting up a
virtual IP address.
Also, is there any problem in running two Master/Primaries?
Just that you'd have to synchronize the zone data between the two manually.
Q2. How does reverse mapping work?
How can reverse lookup possibly work on the Internet - how can a local
> resolver or ISP's Dns server find the pointer records please? E.g. I run
> nslookup 161.114.1.206 & get a reply for a Compaq server
> - how does it know where to look? Is there a giant reverse lookup zone in
> the sky?
Yes, actually, there is: in-addr.arpa.
If
a resolver needs to reverse map, say, 161.114.1.206 to a domain name,
it first inverts the octets of the IP address and appends
"in-addr.arpa." So, in this case, the IP address would become the
domain name 206.1.114.161.in-addr.arpa.
Then
the resolver sends a query for PTR records attached to that domain
name. If necessary, the resolution process starts at the root name
servers. The root name servers refer the querier to the
161.in-addr.arpa name servers, run by an organization called ARIN, the
American Registry for Internet Numbers. These name servers refer the
querier to 1.114.161.in-addr.arpa name servers, run by Compaq. And,
finally, these name servers map the IP address to inmail.compaq.com.
Q3. What are the pros and cons of running slaves versus caching-only name servers?
> Question: I am in the process of setting up dns servers in several locations for my
> business. I have looked into having a primary master server running in my server
> room and adding slave servers in the other areas. I then thought I could just
> setup a primary and a single slave server and run caching only servers in the other
> areas. What are the pros and cons of these two options, or should I run a slave
> server in every location and still have a caching server with it? I just don't
>
know what the best way would be. Please help. The main advantage of
having slaves everywhere is that you have a source of your own zone
data on each name server. So if you have a community of hosts near each
slave that look up domain names in your zones, the local name server
can answer most of their queries. On the other hand, administering
slaves is a little more work than administering caching-only name
servers, and a little greater burden on the primary master name server.
Q4. Can I set a TTL on a specific record?
Is
it possible to setup ttl values for individual records in bind? Sure.
You specify explicit TTLs in a record's TTL field, between the owner
field and the class field: foo. Example. 300 IN A 10.0.0.1
Q5. Can I use an A record instead of an MX record?
> I have a single machine running DNS mail and web for a domain
> and I'm not sure that I have DNS setup properly. If the machine
> that is running the mail is the name of the domain does there need
> to be an MX record for mail?
Technically, no. Nearly all mailers will look up A records for a domain name in a mail destination if no MX records exist.
> If an MX record is not needed, how would you put in an MX
> record for a backup mail server.
You can't. If you want to use a backup mailer, you need to use MX records.
> www cname 192.168.0.1
> mail cname 192.168.0.1
> pop cname 192.168.0.1
> smtp cname 192.168.0.1
These
CNAME records are all incorrect. CNAME records createan alias from one
domain name to another, so the field after "CNAME"must contain a domain
name, not an IP address. For example:www CNAME foo.example.
Q6. What are a zone's NS records used for?
> Could you elaborate a little bit on why do we need to put NS records for
> the zone we are authoritative for ?
> The parent name server handles these already. Is there any problem if our
> own NS records have lower TTLs than the records from parent name server ?
That's a good question. The NS records from your zone data file are used for several things:
-
Your name servers returns them in responses to queries, in the
authority section of the DNS message. Moreover, the set of NS records
that comes directly from your name server supersedes the set that a
querier gets from your parent zone's name servers, so if the two sets
are different, yours "wins."
-
Your name servers use the NS records to determine where to send NOTIFY
messages.- Dynamic updaters determine where to send updates using the
NS records, which they often get from the authoritative name servers.
Q7. Do slaves only communicate with their masters over TCP?
>
When the slave zone checks in with the master zone for the serial
number, is> all this traffic happening on TCP. For example, if you
have acl's blocking> udp traffic but allowing tcp traffic will the
transfer work or will it fail
>
due to the slaves inability to query for the SOA record on udp?No. The
refresh query (for the zone's SOA record) is usually done over UDP.
Q8. What's the largest number I can use in an MX record?
>
Could you tell us the highest possible number we can use for the MX
> preference ?Preference is an unsigned, 16-bit number, so the
largest number you can use is 65535.
Q9. Why are there only 13 root name servers?
> I'm very wondering why there are only 13 root servers on globally.
> Some documents explain that one of the reason is technical limit on Domain
> Name System (without any detailed explanation).
> From my understanding, it seems that some limitation of NS record numbers
> in DNS packet that specified by certain RFCs, or just Internet policy stuff.
>
> Which one is proper reason?
It's
a technical limitation. UDP-based DNS messages can be up to 512
byteslong, and only 13 NS records and their corresponding A records
will fit into a DNS message that size.
Q2. What are their functions?
1.Schema Master
(Forest
level) The schema master FSMO role holder is the Domain Controller
responsible for performing updates to the active directory schema. It
contains the only writable copy of the AD schema. This DC is the only
one that can process updates to the directory schema, and once the
schema update is complete, it is replicated from the schema master to
all other DCs in the forest. There is only one schema master in the
forest.
2.Domain Naming Master
(Forest
level) The domain naming master FSMO role holder is the DC responsible
for making changes to the forest-wide domain name space of the
directory. This DC is the only one that can add or remove a domain from
the directory, and that is it's major purpose. It can also add or
remove cross references to domains in external directories. There is
only one domain naming master in the active directory or forest.
3. PDC Emulator
(Domain level) In a Windows 2000 domain, the PDC emulator server role performs the following functions:
Password changes performed by other DCs in the domain are replicated preferentially to the PDC emulator first.
Authentication
failures that occur at a given DC in a domain because of an incorrect
password are forwarded to the PDC emulator for validation before a bad
password failure message is reported to the user.
Account lockout is processed on the PDC emulator.
Time synchronization for the domain.
Group
Policy changes are preferentially written to the PDC
emulator.Additionally, if your domain is a mixed mode domain that
contains Windows NT 4 BDCs, then the Windows 2000 domain controller,
that is the PDC emulator, acts as a Windows NT 4 PDC to the BDCs.
There is only one PDC emulator per domain.
Note:
Some consider the PDC emulator to only be relevant in a mixed mode
domain. This is not true. Even after you have changed your domain to
native mode (no moreNT 4 domain controllers), the PDC emulator is still
necessary for the reasons above.
4.RID Master
(Domain
level) The RID master FSMO role holder is the single DC responsible for
processing RID Pool requests from all DCs within a given domain. It is
also responsible for removing an object from its domain and putting it
in another domain during an object move. When a DC creates a security
principal object such as a user, group or computer account, it attaches
a unique Security ID (SID) to the object. This SID consists of a domain
SID (the same for all SIDs created in a domain), and a relative ID
(RID) that makes the object unique in a domain. Each Windows 2000 DC in
a domain is allocated a pool of RIDs that it assigns to the security
principals it creates. When a DC's allocated RID pool falls below a
threshold, that DC issues a request for additional RIDs to the domain's
RID master. The domain RID master responds to the request by retrieving
RIDs from the domain's unallocated RID pool and assigns them to the
pool of the requesting DC.There is one RID master per domain in a
directory.
5.Infrastructure Master
(Domain
level) The DC that holds the Infrastructure Master FSMO role is
responsible for cross domain updates and lookups. When an object in one
domain is referenced by another object in another domain, it represents
the reference by the GUID, the SID (for references to security
principals), and the distinguished name (DN) of the object being
referenced. The Infrastructure role holder is the DC responsible for
updating an object's SID and distinguished name in a cross-domain
object reference.
When
a user in DomainA is added to a group in DomainB, then the
Infrastructure master is involved. Likewise, if that user in DomainA,
who has been added to a group in DomainB, then changes his username in
DomainA, the Infrastructure master must update the group membership(s)
in DomainB with the name change.
There is only one Infrastructure master per domain.
Q4. Where are these FSMO server roles found?
The
first domain controller that is installed in a Windows 2000 domain, by
default, holds all five of the FSMO server roles. Then, as more domain
controllers are added to the domain, the FSMO roles can be moved to
other domain controllers.
Q5. Can you Move FSMO roles?
Yes,
moving a FSMO server role is a manual process, it does not happen
automatically. But what if you only have one domain controller in your
domain? That is fine. If you have only one domain controller in your
organization then you have one forest, one domain, and of course the
one domain controller. All 5 FSMO server roles will exist on that DC.
There is no rule that says you have to have one server for each FSMO
server role.
Q6. Where to place the FSMO roles?
Assuming
you do have multiple domain controllers in your domain, there are some
best practices to follow for placing FSMO server roles.
The Schema Master and Domain Naming Master should reside on the same server, and that machine should be a Global Catalog server.
Since all three are, by default, on the first domain controller installed in a forest, then you can leave them as they are.
Note:
According to MS, the Domain Naming master needs to be on a Global
Catalog Server. If you are going to separate the Domain Naming master
and Schema master, just make sure they are both on Global Catalog
servers.
IMP: - Why Infrastructure Master should not be on the same server that acts as a Global Catalog server?
The
Infrastructure Master should not be on the same server that acts as a
Global Catalog server.The reason for this is the Global Catalog
contains information about every object in the forest. When the
Infrastructure Master, which is responsible for updating Active
Directory information about cross domain object changes, needs
information about objects not in it's domain, it contacts the Global
Catalog server for this information. If they both reside on the same
server, then the Infrastructure Master will never think there are
changes to objects that reside in other domains because the Global
Catalog will keep it constantly updated. This would result in the
Infrastructure Master never replicating changes to other domain
controllers in its domain.
Note: In a single domain environment this is not an issue.
Microsoft
also recommends that the PDC Emulator and RID Master be on the same
server. This is not mandatory like the Infrastructure Master and the
Global Catalog server above, but is recommended. Also, since the PDC
Emulator will receive more traffic than any other FSMO role holder, it
should be on a server that can handle the load.
It
is also recommended that all FSMO role holders be direct replication
partners and they have high bandwidth connections to one another as
well as a Global Catalog server.
Q7.What permissions you should have in order to transfer a FSMO role?
Before you can transfer a role, you must have the appropriate permissions depending on which role you plan to transfer:
FSMO TOOLS
Q8. Tools to find out what servers in your domain/forest hold what server roles?
1. Active Directory Users and Computers:-
use
this snap-in to find out where the domain level FSMO roles are located
(PDC Emulator, RID Master, Infrastructure Master), and also to change
the location of one or more of these 3 FSMO roles.
Open
Active Directory Users and Computers, right click on the domain you
want to view the FSMO roles for and click "Operations Masters". A
dialog box (below) will open with three tabs, one for each FSMO role.
Click each tab to see what server that role resides on. To change the
server roles, you must first connect to the domain controller you want
to move it to. Do this by right clicking "Active Directory Users and
Computers" at the top of the Active Directory Users and Computers
snap-in and choose "Connect to Domain Controller". Once connected to
the DC, go back into the Operations Masters dialog box, choose a role
to move and click the Change button.
When you do connect to another DC, you will notice the name of that DC will be in the field below the Change button .
2. Active Directory Domains and Trusts
-
use this snap-in to find out where the Domain Naming Master FSMO role
is and to change it's location.The process is the same as it is when
viewing and changing the Domain level FSMO roles in Active Directory
Users and Computers, except you use the Active Directory Domains and
Trusts snap-in. Open Active Directory Domains and Trusts, right click
"Active Directory Domains and Trusts" at the top of the tree, and
choose "Operations Master". When you do, you will see the dialog box
below.
Changing
the server that houses the Domain Naming Master requires that you first
connect to the new domain controller, then click the Change button. You
can connect to another domain controller by right clicking "Active
Directory Domains and Trusts" at the top of the Active Directory
Domains and Trusts snap-in and choosing "Connect to Domain Controller".
3. Active Directory Schema
-
this snap-in is used to view and change the Schema Master FSMO role.
However... the Active Directory Schema snap-in is not part of the
default Windows 2000 administrative tools or installation. You first
have to install the Support Tools from the \Support directory on the
Windows 2000 server CD or install the Windows 2000 Server Resource Kit.
Once you install the support tools you can open up a blank Microsoft
Management Console (start, run, mmc) and add the snap-in to the
console. Once the snap-in is open, right click "Active Directory
Schema" at the top of the tree and choose "Operations Masters". You
will see the dialog box below.
Changing
the server the Schema Master resides on requires you first connect to
another domain controller, and then click the Change button.You can
connect to another domain controller by right clicking "Active
Directory Schema" at the top of the Active Directory Schema snap-in and
choosing "Connect to Domain Controller
4.Netdom
The easiest and fastest way to find out what server holds what FSMO role is by using the
Netdom
command line utility. Like the Active Directory Schema snap-in, the
Netdom utility is only available if you have installed the Support
Tools from the Windows 2000 CD or the Win2K Server Resource Kit.To use
Netdom to view the FSMO role holders, open a command prompt window and
type:netdom query fsmo and press enter. You will see a list of the FSMO
role servers:
5. Active Directory Relication Monitor
another tool that comes with the Support Tools is the
Active Directory Relication Monitor
.
Open this utility from Start, Programs, Windows 2000 Support Tools.
Once open, click Edit, Add Monitored Server and add the name of a
Domain Controller. Once added, right click the Server name and choose
properties. Click the FSMO Roles tab to view the servers holding the 5
FSMO roles (below). You cannot change roles using Replication Monitor,
but this tool has many other useful purposes in regard to Active
Directory information. It is something you should check out if you
haven't already.
Finally, you can use the
Ntdsutil.exe utility
to gather information about and change servers for FSMO roles. Ntdsutil.exe,
a command line utility that is installed with Windows 2000 server, is
rather complicated and beyond the scope of this document.
6. DUMPFSMOS
Command-line
tool to query for the current FSMO role holders Part of the Microsoft
Windows 2000 Server Resource Kit Downloadable fromhttp://www.microsoft.com/windows2000/techinfo/reskit/default.aspPrints to the screen, the current FSMO holders Calls NTDSUTIL to get this information
7. NLTEST
Command-line
tool to perform common network administrative tasks Type “nltest /?”
for syntax and switches Common uses Get a list of all DCs in the domain
Get the name of the PDC emulator Query or reset the secure channel for
a server Call DsGetDCName to query for an available domain controller
8. Adcheck (470k)
(3rd party) A simple utility to view information about AD and FSMO roleshttp://www.svrops.com/svrops/downloads/zipfiles/ADcheck.msi
Q9. How to Transfer and Seize a FSMO Role?
GROUP POLICY
Q1. What are Group Policies?
Group
Policies are settings that can be applied to Windows computers, users
or both. In Windows 2000 there are hundreds of Group Policy settings.
Group Policies are usually used to lock down some aspect of a PC.
Whether you don't want users to run Windows Update or change their
Display Settings, or you want to insure certain applications are
installed on computers - all this can be done with Group Policies.Group
Policies can be configured either
Locally or by Domain Polices
.
Local policies can be accessed by clicking Start, Run and typing
gpedit.msc. They can also be accessed by opening the Microsoft
Management Console (Start, Run type mmc), and adding the Group Policy
snap-in. You must be an Administrator to configure/modify Group
Policies. Windows 2000 Group Policies can only be used on Windows 2000
computers or Windows XP computers. They cannot be used on Win9x or
WinNT computers.
Q2. Domain policy gets applied to whom ?
Domain
Policies are applied to computers and users who are members of a
Domain, and these policies are configured on Domain Controllers. You
can access Domain Group Polices by opening Active Directory Sites and
Services (these policies apply to the Site level only) or Active
Directory Users and Computers (these policies apply to the Domain
and/or Organizational Units).
Q3. From Where to create a Group Policy?
To
create a Domain Group Policy Object open Active Directory Sites and
Services and right click Default-First-Site-Name or another Site name,
choose properties, then the Group Policy tab, then click the
New button Give the GPO a name, then click the Edit button to configure the policies.
For Active Directory Users and Computers, it the same process except you right click the Domain or an OU and choose properties.
Q4. Who can Create/Modify Group Policies?
You
have to have Administrative privileges to create/modify group policies.
The following table shows who can create/modify group policies:
Q5. How are Group Policies Applied?
Group
Polices can be configured locally, at the Site level, the Domain level
or at the Organizational Unit (OU) level. Group Policies are applied in
a Specific Order, LSDO -
Local
policies first, then Site based policies, then Domain level policies,
then OU polices, then nested Polices (OUs within OUs). Group polices
cannot be linked to a specific user or group, only container objects.
In order to apply Group Polices to specific users or computers, you add
users (or groups) and computers to container objects. Anything in the
container object will then get the policies linked to that container.
Sites, Domains and OUs are considered container objects. Computer and
User Active Directory objects do not have to put in the same container
object. For example, Sally the user is an object in Active Directory.
Sally's Windows 2000 Pro PC is also an object in Active Directory.
Sally the user object can be in one OU, while her computer object can
be another OU. It all depends on how you organize your Active Directory
structure and what Group Policies you want applied to what objects.
There
are two nodes in each Group Policy Object that is created. A Computer
node and a User Node. They are called Computer Configuration and User
Configuration (see image above). The polices configured in the Computer
node apply to the computer as a whole. Whoever logs onto that computer
will see those policies.
Note: Computer policies are also referred to as machine policies.
User
policies are user specific. They only apply to the user that is logged
on. When creating Domain Group Polices you can disable either the
Computer node or User node of the Group Policy Object you are creating.
By disabling a node that no policies are defined for, you are
decreasing the time it takes to apply the polices.
To disable the node polices:
After creating a Group Policy Object, click that Group Policy Object on
the Group Policy tab, then click the Properties button. You will see
two check boxes at the bottom of the General tab.
It's
important to understand that when Group Policies are being applied, all
the policies for a node are evaluated first, and then applied. They are
not applied one after the other. For example, say Sally the user is a
member of the Development OU, and the Security OU. When Sally logs onto
her PC the policies set in the User node of the both the Development OU
and the Security OU Group Policy Objects are evaluated, as a whole, and
then applied to Sally the user. They are not applied Development OU
first, and then Security OU (or visa- versa).The same goes for Computer
policies. When a computer boots up, all the Computer node polices for
that computer are evaluated, and then applied.
When
computers boot up, the Computer policies are applied. When users login,
the User policies are applied. When user and computer group policies
overlap, the computer policy wins
Note: IPSec and EFS policies are not additive. The last policy applied is the policy the user/computer will have
When
applying multiple Group Policies Objects from any container, Group
Policies are applied from bottom to top in the Group Policy Object
list. The top Group Policy in the list is the last to be applied. In
the above image you can see three Group Policy Objects associated with
the Human Resources OU. These polices would be applied No Windows
Update first, then No Display Settings, then No Screen Saver. If there
were any conflicts in the policy settings, the one above it would take
precedence.
Q6.How to disable Group Policy Objects?
When
you are creating a Group Policy Object, the changes happen immediately.
There is no "saving" of GPOs. To prevent a partial GPO from being
applied,
disable
the GPO while you are configuring it. To do this, click the Group
Policy Object on the Group Policy tab and under the Disable column,
double click - a little check will appear. Click the Edit button, make
your changes, then double click under the Disable column to re-enable
the GPO. Also, if you want to temporarily disable a GPO for
troubleshooting reasons, this is the place to do it. You can also click
the Options button on the Group Policy tab and select the Disabled
check box.
Q7. When does the group policy Scripts run?
Startup scripts are processed at computer boot up and before the user logs in.
Shutdown scripts are processed after a user logs off, but before the computer shuts down.
Login scripts are processed when the user logs in.
Log off scripts are processed when the user logs off, but before the shutdown script runs.
Q8. When the group policy gets refreshed/applied?
Group
Policies can be applied when a computer boots up, and/or when a user
logs in. However, policies are also refreshed automatically according
to a predefined schedule. This is called
Background Refresh
Background
refresh for non DCs (PCs and Member Servers) is every 90 mins., with a
+/- 30 min.interval. So the refresh could be 60, 90 or 120 mins.
For DCs (Domain Controllers), background refresh is every 5 mins.Also, every 16 hours
every
PC will request all group policies to be reapplied (user and machine)
These settings can be changed under Computer and User Nodes,
Administrative Templates,System, Group Policy.
Q9. Which are the policies which does not get affected by background refresh?
Policies not affected by background refresh. These policies are only applied at
Logon time:
Folder Redirection
Software InstallationLogon,
Logoff, Startup,
Shutdown Scripts
Q9. How to refresh Group Policies suing the command line?
Secedit.exe
is a command line tool that can be used to refresh group policies on a
Windows 2000 computer. To use secedit, open a command prompt and type:
secedit /refreshpolicy user_policy to refresh the user policies
secedit
/refreshpolicy machine_policy to refresh the machine (or computer)
policies These parameters will only refresh any user or computer
policies that have changed since the last refresh. To force a reload of
all group policies regardless of the last change, use:
secedit /refreshpolicy user_policy /enforce
secedit /refreshpolicy machine_policy /enforce
Gpupdate.exe
is a command line tool that can be used to refresh group policies on a
Windows XP computer. It has replaced the secedit command. To use
gpupdate, open a command prompt and type:
gpupdate /target:user to refresh the user policies
gpupdate /target: machine to refresh the machine (or computer) policies
As
with secedit, these parameters will only refresh any user or computer
policies that have changed since the last refresh. To force a reload of
all group policies regardless of the last change, use:
gpupdate /force
Notice
the /force switch applies to both user and computer policies. There is
no separation of the two like there is with secedit
Q10. What is the Default Setting for Dial-up users?
Win2000
considers a slow dial-up link as anything less than 500kbps. When a
user logs into a domain on a link under 500k some policies are not
applied. Windows 2000 will automatically detect the speed of the
dial-up connection and make a decision about applying Group Policies.
Q11. Which are the policies which get applied regardless of the speed of the dial-up connection?
Some policies are always applied regardless of the speed of the dial-up connection. These are:
Administrative Templates
Security Settings
EFS Recovery
IPSec
Q12. Which are the policies which do not get applied over slow links?
IE Maintenance Settings
Folder Redirection Scripts
Disk Quota settings
Software Installation and Maintenance
These settings can be changed under Computer and User Nodes, Administrative Templates, System, Group Policy.
If
the user connects to the domain using "Logon Using Dial-up Connection"
from the logon screen, once the user is authenticated, the computer
policies are applied first, followed by the user policies.
If
the user connects to the domain using "Network and Dial-up
Connections", after they logon, the policies are applied using the
standard refresh cycle.
Q13. Which are the two types of default policies?
There
are two default group policy objects that are created when a domain is
created. The Default Domain policy and the Default Domain Controllers
policy.
Default Domain Policy-
this GPO can be found under the group policy tab for that domain. It is
the first policy listed. The default domain policy is unique in that
certain policies can only be applied at the domain level.
If
you double click this GPO and drill down to Computer Configuration,
Windows Settings, Security Settings, Account Policies, you will see
three policies listed:
Password Policy
Account Lockout Policy
Kerberos Policy
These 3 policies can only be set at the domain level. If you set these policies anywhere else- Site or OU, they are ignored. However,
setting these 3 policies at the OU level will have the effect of
setting these policies for users who log on locally to their PCs. Login
to the domain you get the domain policy, login locally you get the OU
policy.
If
you drill down to Computer Configuration, Windows Settings, Security
Settings, Local Policies, Security Options, there are 3 policies that
are affected by Default Domain Policy:
Automatically log off users when logon time expires
Rename Administrator Account - When set at the domain level, it affects the Domain Administrator account only.
Rename Guest Account - When set at the domain level, it affects the Domain Guest account only.
The
Default Domain Policy should be used only for the policies listed
above. If you want to create additional domain level policies, you
should create additional domain level GPOs. Do not delete the Default
Domain Policy. You can disable it, but it is not recommended.
Default Domain Controllers Policy
-
This policy can be found by right clicking the Domain Controllers OU,
choosing Properties, then the Group Policy tab. This policy affects all
Domain Controllers in the domain regardless of where you put the domain
controllers. That is, no matter where you put your domain controllers
in Active Directory (whatever OU you put them in), they will still
process this policy. Use the Default Domain Controllers Policy to set
local policies for your domain controllers, e.g. Audit Policies, Event Log settings, who can logon locally and so on.
Q14.How to restore Group policy setting back to default?
The
following command would replace both the Default Domain Security Policy
and DefaultDomain Controller Security Policy. You can specify Domain or
DC instead of Both, to onlyrestore one or the other.
> dcgpofix /target:Both
Note that this must be run from a domain controller in the target domain where you want to reset the GPO
If
you've ever made changes to the default GPOs and would like to revert
back to the original settings, the dcgpofix utility is your solution.
dcgpofix works with a particular version of schema. If the version it
expects to be current is different from what is in Active Directory,
itnot restore the GPOs. You can work around this by using the
/ignoreschema switch, whichrestore the GPO according to the version
dcgpofix thinks is current. The only time you mightexperience this
issue is if you install a service pack on a domain controller (dc1)
that extendsschema, but have not installed it yet on a second domain
controller (dc2). If you try to run
dcgpofix from dc2, you will receive the error since a new version of the schema and thedcgpofix utility was installed on dc1.
Resolving GPOs from Multiple Sources
Because
GPOs can come from different sources to apply to a single user or
computer, there must be a way of determining how those GPOs are
combined. GPOs are processed in the following order:
1. Local GPO The local GPO on the computer is processed and all settings specified in that GPO are applied.
2. Site GPOs GPOs
linked to the site in which the computer resides are processed.
Settings made at this level override any conflicting settings made at
the preceding level. If multiple GPOs are linked to a site, the site
administrator can control the order in which those GPOs are processed.
3. Domain GPOs GPOs
linked to the domain in which the computer resides are processed and
any settings are applied. Settings made at the domain level override
conflicting settings applied at the local or site level. Again, the
administrator can control the processing order when multiple GPOs are
linked to the domain.
4. OU GPOs GPOs
linked to any OUs that contain the user or computer object are
processed. Settings made at the OU level override conflicting settings
applied at the domain, local, or site level. It is possible for a
single object to be in multiple OUs. In this case, GPOs linked to the
highest level OU in the Active Directory hierarchy are processed first,
followed by the next highest level OU, and so on. If multiple GPOs are
linked to a single
.
Q15. What are the two exceptions to control the inheritance of the group policy?
■ No Override
When
you link a GPO to a container, you can configure a No Override option
that prevents settings in the GPO from being overridden by settings in
GPOs linked to child containers. This provides a way to force child
containers to conform to a particular policy.
■ Block Inheritance
You
can configure the Block Inheritance option on a container to prevent
the container from inheriting GPO settings from its parent containers.
However, if a parent container has the No Override option set, the
child container cannot block inheritance from this parent.
Q16. How to Redirect New User and Computer Accounts?
By
default, new user and computer accounts are created in the Users and
Computers containers, respectively. You cannot link a GPO to either of
these built-in containers. Even though the built-in containers inherit
GPOs linked to the domain, you may have a situation that requires user
accounts and computer accounts to be stored in an OU to which you can
link a GPO. Windows Server 2003 includes two new tools that let you
redirect the target locationfor new user and computer accounts. You can
use redirusr.exe to redirect user accounts and redircomp.exe to
redirect computer accounts. Once you choose the OU for redirection, new
user and computer accounts are createddirectly in the new target OU,
where the appropriate GPOs are linked. For example, you could create an
OU named New Users, link an appropriate GPO to the OU, and then
redirect the creation of new-users accounts to the New Users OU. Any
new users created would immediately be affected by the settings in the
GPO. Administrators could then move the new user accounts to a more
appropriate location later. You can find both of these tools in the
%windir%\system32 folder on any computer running Windows Server 2003.
You can learn more about using these tools in Knowledge Base article
324949, “Redirecting the Users and Computers Containers in Windows
Server 2003 Domains,” in the Microsoft Knowledge Base at
http://support.microsoft.com
.
Q17. What permissions should a administrator have to manage GPOs?
Editing GPOs linked to sites requires Enterprise Administrative permissions.
Editing GPOs linked to domains requires Domain Administrative
Editing GPOs linked to OUs requires permissions for the OU.
Q18. What is the client requirement for supporting GPOs?
For
client computers to accept Group Policy settings, they must be members
of Active Directory. Support for Group Policy for key operating systems
includes the following:
■ Windows 95/98/Me do not support Group Policy.
■ Windows NT 4.0 and earlier versions do not support Group Policy.
■
Windows 2000 Professional and Server support many of the Group Policy
settings available in Windows Server 2003, but not all. Unsupported
settings are ignored.
■ Windows XP Professional, Windows XP 64-bit Edition, and Windows Server 2003 fully support Group Policy.
Hi Ashok,
ReplyDeleteThanks for sharing your insightful thoughts and suggestions - very helpful, and appreciated indeed.
On a related note, we needed a quick and efficient way to enumerate nested security groups for security audits (i.e. find out which groups were nested in other groups.) So we asked our on-site MS consultant and he recommended using the Gold Finger from Paramount Defenses Inc.
Gold Finger pleasantly surprised us because not only was it endorsed by Microsoft but also 100% FREE and loaded with almost 250 useful Active Directory security, Exchange and ACL management reports. BTW, you can download it for free from http://goldfinger.paramountdefenses.com
Thought I'd share this with you incase it could help you too, especially if you're into AD security reporting.
Thanks again, and looking forward to your next post.
Best wishes,
Jonathan