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Active Directory
Active Directory is a set of networking services made by Microsoft. Questions about using and configuring Active Directory belong here.
849 Questions
What is the centralized directory database in the domain model SAM?
the centralized directory database in the domain model
is NTDS.DIT(directory information tree)
but for the local sstem not connected to domain is SAM
FSMO Role Loss implications
Schema The schema cannot be extended. However, in the short term no one will notice a missing Schema Master unless you plan a schema upgrade during that time.
Domain Naming Unless you are going to run DCPROMO, then you will not miss this FSMO role.
RID Chances are good that the existing DCs will have enough unused RIDs to last some time, unless you're building hundreds of users or computer object per week.
PDC Emulator Will be missed soon. NT 4.0 BDCs will not be able to replicate, there will be no time synchronization in the domain, you will probably not be able to change or troubleshoot group policies and password changes will become a problem.
Infrastructure Group memberships may be incomplete. If you only have one domain, then there will be no impact.
FSMO seizing restrictions:
FSMO Role Restrictions
Original must be reinstalled
Schema
Domain Naming
Can transfer back to original
RID
PDC Emulator
Infrastructure
steps to seize and transfer
1. On any domain controller, click Start, click Run, type Ntdsutil in the Open box, and then click OK.
C:\WINDOWS>ntdsutil
ntdsutil:
1. Type roles, and then press ENTER.
ntdsutil: roles
fsmo maintenance:
Note: To see a list of available commands at any of the prompts in the Ntdsutil tool, type ?, and then press ENTER.
1. Type connections, and then press ENTER.
fsmo maintenance: connections
server connections:
1. Type connect to server <servername>, where <servername> is the name of the server you want to use, and then press ENTER.
server connections: connect to server server100
Binding to server100 ...
Connected to server100 using credentials of locally logged on user.
server connections:
1. At the server connections: prompt, type q, and then press ENTER again.
server connections: q
fsmo maintenance:
1. Type seize <role>, where <role> is the role you want to seize. For example, to seize the RID Master role, you would type seize rid master:
Options are:
Seize domain naming master
Seize infrastructure master
Seize PDC
Seize RID master
Seize schema master
1. You will receive a warning window asking if you want to perform the seize. Click on Yes.
fsmo maintenance: Seize infrastructure master
Attempting safe transfer of infrastructure FSMO before seizure.
ldap_modify_sW error 0x34(52 (Unavailable).
Ldap extended error message is 000020AF: SvcErr: DSID-03210300, problem 5002 (UNAVAILABLE)
, data 1722
Win32 error returned is 0x20af(The requested FSMO operation failed. The current FSMO holde
r could not be contacted.)
)
Depending on the error code this may indicate a connection,
ldap, or role transfer error.
Transfer of infrastructure FSMO failed, proceeding with seizure ...
Server "server100" knows about 5 roles
Schema - CN=NTDS Settings,CN=SERVER200,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
Domain - CN=NTDS Settings,CN=SERVER100,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
PDC - CN=NTDS Settings,CN=SERVER100,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
RID - CN=NTDS Settings,CN=SERVER200,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
Infrastructure - CN=NTDS Settings,CN=SERVER100,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
fsmo maintenance:
Note: All five roles need to be in the forest. If the first domain controller is out of the forest then seize all roles. Determine which roles are to be on which remaining domain controllers so that all five roles are not on only one server.
1. Repeat steps 6 and 7 until you've seized all the required FSMO roles.
2. After you seize or transfer the roles, type q, and then press ENTER until you quit the Ntdsutil tool.
Note: Do not put the Infrastructure Master (IM) role on the same domain controller as the Global Catalog server. If the Infrastructure Master runs on a GC server it will stop updating object information because it does not contain any references to objects that it does not hold. This is because a GC server holds a partial replica of every object in the forest
What is replication in active directory and how it is done?
the Active Directory database is replicated between domain controllers. The data replicated between controllers called "data" are also called "naming context". Only the changes are replicated, once a domain controller has been established. Active Directory uses a multimaster model which means changes can be made on any controller and the changes are sent to all other controllers. The replication path in Active Directory forms a ring which adds reliability to the replication.
How Replication is Tracked
* USN - Each object has an Update Sequence Number (USN), and if the object is modified, the USN is incremented. This number is different on each domain controller.
* Stamps - Each object has a stamp with the version number, timestamp, and the GUID of the domain controller where the change was made
Domain controllers each contain a "replica" which is a copy of the domain directory. The "directory update type" indicates how the data is replicated. The two types are:
* Origination update - A change made by an administrator at the local domain controller.
* Replicated update - A change made to the replica because of a replication from a replication partner.
Replication Sequence
Terms:
* Latency - The required time for all updates to be completed throughout all comain controllers on the network domain or forest.
* Convergence - The state at which all domain controllers have the same replica contents of the Active directory database.
* Loose consistency - The state at which all changes to the database are not yet replicated throughout all controllers in the database (not converged).
1. A change is made to the Active Directory database on a domain controller. The attribute of the object and the new USN is written to the database. The entire object is NOT replicated. This is called an atomic operation becuase both changes are done, or neither change is done. This is an origination update. There are four types:
* Add - An object is added to the database.
* Delete - An object is deleted from the database.
* Modify - An object in the database has its attributes modified.
* Modify DN - An object is renamed or moved to another domain.
2. The controller the change was made on (after five minutes of stablilty), notifies its replication partners that a change was made. It sends a change notification to these partners, but only notifies one partner every 30 seconds so it is not overwhelmed with update requests. Each controller, in turn, when it is updated, sends a change notice to its respective replication partners.
3. The replication partners each send an update request with a USN to the domain controller that the change was made on. The USN identifies the current state of the domain controller making the change. Each change has a unique USN. This way the domain controller that has the change knows the state of the domain controller requesting the changes and only the changes are required to be sent. The time on each controller, therefore, does not need to be synchronized exactly although timestamps are used to break ties regarding changes.
4. Changes are made through replication partners until all partners are replicated. At some point, replication partners will attempt to replicate partners that are already updated. This is where propagation dampening is used.
If no changes have been performed in six hours, replication procedures are performed to be sure no information has been missed.
Information sent during an update includes:
* Updated object
* The GUID and USN of the domain server with the originating update.
* A local USN of the update on the updated object.
Replication Path
The replication path that domain controller Active Directory replicated data travels through an enterprise is called the replication topology. Connection objects are used to define the replication paths between domain controllers. Active Directory, by default, sets up a two way ring replication path. The data can travel in both directions around the ring which provides redundancy and reliability. Two types of replication occur in the path:
* Direct replication - When replication is done from a primary source of data.
* Transitive replication - When replication is done from a secondhand or replicated source of data.
The Knowledge Consistency Checker (KCC) (running on all domain controllers) generates the replication topology by specifying what domain controllers will replicate to which other domain controllers in the site. The KCC maintains a list of connections, called a replication topology, to other domain controllers in the site. The KCC ensures that changes to any object are replicated to all site domain controllers and updates go through no more than three connections. Also an administrator can configure connection objects.
The KCC uses information provided by the administrator about sites and subnets to automatically build the Active Directory replication topology.
Propagation Dampening
Terms:
* Propagation dampening is used to prevent unnecessary replication by preventing updates from being sent to servers that are already updated. Each domain controller keeps a list of other known domain controllers and the last USN received from each controller. Two up-to-date vector numbers support this:
o Replica GUID
o Update Sequence Number (USN) - Mentioned earlier it is incremented anytime an origination or replicated update is received. The USN stored is from the originating server. It is stored as metadata with:
+ An attribute indicating "added" or "changed" for the object being updated.
+ The GUID (above).
+ A local USN for the object attribute changed.
+ The changed data.
The up-to-date vector numbers are incremented when replication occurs with the originating server. Each domain controller has its own different USN (They may not start at the same number). The highest USN from each domain controller that is stored in other domain controllers is called the high watermark for that domain controller.
* Propagation delay describes the amount of time required for a change to be replicated to domain controllers throughout the domain.
* Ring Topology - The Active Directory replication process uses a ring topology where the replication partners form a ring. This adds reliability to the process and also helps decrease propagation delay.
The information sent in an update request includes the high water mark entry for the originating server for the last change received. If the highwater mark received from the server that sent the update request is the same as the highwatermark for the originating server on the server receiving the request, the receiving server will not send the replicated information.
The usnChanged parameter is the highest USN number for any object.
Replication Partitions
Types of Active Directory data storage categories which are called partitions:
* Schema partition - Defines rules for object creation and modification for all objects in the forest. Replicated to all domain controllers in the forest. Replicated to all domain controllers in the forest, it is known as an enterprise partition.
* Configuration partition - Information about the forest directory structure is defined including trees, domains, domain trust relationships, and sites (TCP/IP subnet group). Replicated to all domain controllers in the forest, it is known as an enterprise partition.
* Domain partition - Has complete information about all domain objects (Objects that are part of the domain including OUs, groups, users and others). Replicated only to domain controllers in the same domain.
o Partial domain directory partition - Has a list of all objects in the directory with a partial list of attributes for each object.
These partitions are all replicated between domain controllers by Active directory. Different partitions may be replicated between different replication partners.
Replication Conflict
Replication conflict occurs when changes are made to the same object and attribute before the changes can be replicated throughout all domain controller's copies of the database. Additional data (metadata) stored for each object attribute includes (not related to USN):
* Time stamp of the last change.
* Attribute version number - For each object's attributes, this value is the same on all domain controllers.
When an Active Directory database update is received on a domain controller, one of the following happens:
* If the update attribute version number is higher than the current version number on the controller, the new value of the attribute is stored and the version number is updated.
* If the update attribute version number and stored attribute version number are the same, timestamps are used to resolve the conflict.
* If the both version numbers and both timestamps are the same, the update from the controller with the highest GUID is used.
File Replication Service
In Windows 2000, the SYSVOL share is used to to authenticate users. The SYSVOL share includes group policy information which is replicated to all local domain controllers. File replication service (FRS) is used to replicate the SYSVOL share. The "Active Directory Users and Computers" tool is used to change the file replication service schedule.
Intrasite Replication
Replication that happens between controllers inside one site. All of the subnets inside the site should be connected by high speed network wires. Replication between two sites may need to be sent over a slower WAN link or leased line. Intrasite replication data is sent uncompressed.
Site replication is done using Remote Procedure Call (RPC). If a change is made, replication occurs within five minutes, and replication is done every six hours if no changes were made. Domain controllers that receive updates replicate that information to other domain controllers on their route list. All changes are therefore completed within a site within 15 minutes since there can only be three hops.
The topology used here is the ring topology talked about earlier and this replication is automatically set up by Active Directory, but may be modified by an administrator.
DNS Replication
The DNS IP address and computer name is stored in Active Directory for Active Directory integrated DNS zones and replicated to all local domain controllers. DNS information is not replicated to domain controllers outside the domain.
Intersite Replication
Intrasite replication is replication between sites and must be set up by an administrator.
Replication Management
The administrative tool, "Active Directory Sites and Services", is used to manage Active Directory replication. Replication data is compressed before being sent to minimze bandwidth use. There are two protocols used to replicate AD:
* Normally Remote Procedure Call (RPC) is used to replicate data and is always used for intrasite replication since it is required to support the FRS. RPC depends on IP (internet protocol) for transport.
* Simple Mail Transfer Protocol (SMTP) may be used for replication between sites.
SMTP can't replicate the domain partition, however. Therefore the remote site would need to be in another domain to be able to effectively use SMTP for carrying replication data.
Bridgehead server - A domain controller that is used to send replication information to one or more other sites.
Flexible Single Master Operations (FSMO) (discussed in an earlier section) can be transferred manually to various domain controllers. Roles and tools used to transfer are:
* Schema Master - Use "Active Directory Domains and Trusts". Makes changes to the database schema. Applications may remotely connect to the schema master.
* Domain Naming Master - Use the MMC "Active Directory Schema Snap-in". Adds or removes domains to or from the forest.
* Primary Domain Controller (PDC) Emulator - Use the "Active Directory Users and Computers" administrative tool. When Active Directory is in mixed mode, the computer Active Directory is on acts as a Windows NT PDC. Mixed mode occurs when Active Directory interfaces with NT 4.0 BDCs or ones without Windows 2000 Directory Service client software. In mixed mode, computers without Windows 2000 client software must contact the PDC emulator to change user account information.
* Relative ID Master (RID Master) - Use the "Active Directory Users and Computers" administrative tool. All objects have a Security Identifier (SID) and a domain SID. The RID assigns relative IDs to each domain controller.
* Infrastructure Master - Use the "Active Directory Users and Computers" administrative tool. Updates group membership information when users from other domains are moved or renamed.
Any master role can be transferred by using the command line program, ntdsutil.exe. When a server performing a master role fails and goes offline, you can perform "seizing master operations" to have another server perform that role. Only the ntdsutil.exe program can perform this function. Commands include:
* connections - A connections prompt appears:
o connect to server "FQDN of server to connect to"
o quit
* sieze "name of role to transfer". Role names are:
o PDC
o RID master
o schema master
o domain naming master
o infastructure master
Example: "sieze RID master"
Replication Associated Performance Monitor Counters
* DRA Inbound Bytes Not Compressed - Replicated uncompressed bytes that are probably from a Directory Services Agent (another controller sending data) in the same site.
* DRA Inbound Bytes Compressed (Before Compression) - Replicated bytes received (as though in uncompressed form).
* DRA Inbound Bytes Not Compressed (After Compression) - Replicated bytes received (as in compressed form).
* DRA Inbound Bytes Total The sum of the DRA Inbound Bytes Not Compressed plus the DRA Inbound Bytes Not Compressed (After Compression).
* DRA Outbound Bytes Not Compressed - Replicated uncompressed bytes that are being sent to another domain controller in the same site.
Schema Cache
A schema cache which is a copy of the schema in memory can be used to speed up schema queries but should be used sparingly due to the high memory requirements. If the schemaUpdateNow attribute is added to the RootDSE a schema cache update is done immediately. Normally the schema cache is stored in memory when the system boots and updated every five minutes.
How do you find a dns server address?
ipconfig /all
Look through the data to see what your DNS address is.
If you are using a Mac. Go to the System Preferences. Click on the Network Icon Double Click on the Ethernet icon if you have an ethernet cable plugged in (Looks like a wide phone jack) Double Click on the Airport card if you are using wireless internet. The DNS servers will be listed under the TCP/IP Tab.
Can you copy GPOs from one domain to another domain?
In fact, the answer is YES!!! With the GPMC, you can most definately accomplish this, and the steps required are, for the most part, relatively straight forward. Microsoft has released a white paper that discusses this very topic which you can download
Active directory information is stored on each domain controller in a file called?
The Active Directory database is stored on each domain controller in a file called NTDS.DIT
PWD
Personal Identifier Number (PIN)
What are gpo in Active Directory?
Group Policy Objects (GPOs) are collections of settings for Windows operating systems.
In general terms, they are created for two reasons: to control the look and feel of the operating system and its functionality (the "user experience") or to govern the way the system works such as its security and operation.
Administrators have been able to apply policies to machines since Windows 9x/NT3 but with the advent of Active Directory in Windows 2000, GPOs have allowed a granular centralised control mechanism for domain members ranging across almost all aspects of the OS and many of the Microsoft products (primarily Internet Explorer and the Office suite, although customisation allows virtually any application to be controlled).
Group Policy settings can apply either to the machine itself (and consequently apply to all users of that machine) or to groups of users of the machine. They grant the ability to standardise an estate.
In large organisations, they are used to control password policies, logon rights, privileges, permissions, registry settings, the desktop and the underlying security of the infrastructure. They are vital in maintaining control and governance.
As examples of their capabilities, you can set all machines to have the same colour scheme, screensaver, minimum password length/complexity, or any of the thousands of options available. They can be used to roll out software, fire startup and logon scripts, and enable/disable services, etc.
The GLobal Catalogue has a reference to all objects within Active Directory. Its is know as GC
What are the five FSMO roles in Active Directory forest with one parent and two child domains?
There are five roles:
They are further classified in two
1. Forest Roles- Schema Master - As name suggests, the changes that are made while creation of any object in AD or changes in attributes will be made by single domain controller and then it will be replicated to another domain controllers that are present in your environment. There is no corruption of AD schema if all the domain controllers try to make changes. This is one of the very important roles in FSMO roles infrastructure.
- Domain Naming Master - This role is not used very often, only when you add/remove any domain controllers. This role ensures that there is a unique name of domain controllers in environment.
- Infrastructure Master - This role checks domain for changes to any objects. If any changes are found then it will replicate to another domain controller.
- RID Master - This role is responsible for making sure each security principle has a different identifier.
- PDC emulator - This role is responsible for Account policies such as client password changes and time synchronization in the domain
It depends on your setup. If this all of the computers are networked in a workgroup environment, then you need to have a locally stored profile on each computer that redirects to the master fileserver. The SAM will be the database in this case
If you have a domain environment, then just join all of the computers into the domain and they should be able to log on to any computer on the network.The AD will take care of security nad NTDS.DIT will be database in this case
Which utility allows you to create Active Directory trust relationships from the command line?
netdom
Netdom
yes and it is recommended that the roles should be seized and transferred to a healthy DC
They way to transfer is as follows
1. On any domain controller, click Start, click Run, type Ntdsutil in the Open box, and then click OK.
C:\WINDOWS>ntdsutil
ntdsutil:
1. Type roles, and then press ENTER.
ntdsutil: roles
fsmo maintenance:
Note: To see a list of available commands at any of the prompts in the Ntdsutil tool, type ?, and then press ENTER.
1. Type connections, and then press ENTER.
fsmo maintenance: connections
server connections:
1. Type connect to server <servername>, where <servername> is the name of the server you want to use, and then press ENTER.
server connections: connect to server server100
Binding to server100 ...
Connected to server100 using credentials of locally logged on user.
server connections:
1. At the server connections: prompt, type q, and then press ENTER again.
server connections: q
fsmo maintenance:
1. Type seize <role>, where <role> is the role you want to seize. For example, to seize the RID Master role, you would type seize rid master:
Options are:
Seize domain naming master
Seize infrastructure master
Seize PDC
Seize RID master
Seize schema master
1. You will receive a warning window asking if you want to perform the seize. Click on Yes.
fsmo maintenance: Seize infrastructure master
Attempting safe transfer of infrastructure FSMO before seizure.
ldap_modify_sW error 0x34(52 (Unavailable).
Ldap extended error message is 000020AF: SvcErr: DSID-03210300, problem 5002 (UNAVAILABLE)
, data 1722
Win32 error returned is 0x20af(The requested FSMO operation failed. The current FSMO holde
r could not be contacted.)
)
Depending on the error code this may indicate a connection,
ldap, or role transfer error.
Transfer of infrastructure FSMO failed, proceeding with seizure ...
Server "server100" knows about 5 roles
Schema - CN=NTDS Settings,CN=SERVER200,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
Domain - CN=NTDS Settings,CN=SERVER100,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
PDC - CN=NTDS Settings,CN=SERVER100,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
RID - CN=NTDS Settings,CN=SERVER200,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
Infrastructure - CN=NTDS Settings,CN=SERVER100,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dpetri,DC=net
fsmo maintenance:
Note: All five roles need to be in the forest. If the first domain controller is out of the forest then seize all roles. Determine which roles are to be on which remaining domain controllers so that all five roles are not on only one server.
1. Repeat steps 6 and 7 until you've seized all the required FSMO roles.
2. After you seize or transfer the roles, type q, and then press ENTER until you quit the Ntdsutil tool.
Note: Do not put the Infrastructure Master (IM) role on the same domain controller as the Global Catalog server. If the Infrastructure Master runs on a GC server it will stop updating object information because it does not contain any references to objects that it does not hold. This is because a GC server holds a partial replica of every object in the forest
Enterprise Admins.
What services does Next Directory offer to its customers?
NextDirectory is a British website offering clothing for men, women and children, as well as a small range of homewares. Next is a large retail group with hundreds of physical stores as well as a large online presence.
What is the Active Directory organizational unit?
- Open Active Directory Users and Computers.
- In the console tree, right-click the folder in which you want to add an organizational unit.
Where?
- Active Directory Users and Computers/domain node/folder
- Point to New, and then click Organizational Unit.
- Type the name of the organizational unit.
The administrator of the first domain in a forest is called the?
The administrator .he/she is part of administrators group and has all rights in the domain.The entreprise admin has all the rights on the forest/domain both are default groups.You can rename your administrator's name and make him part of this group.
What are authoritative dns server and none authoritative dns server?
authoritative dns server is server that has own databases that has name resolution for the clients that for resolve from name to ip address and for ip address to name.
non-authorititative dns server is server that forward request of dns client to authoritative dns server for resolve.
Why is dns a requirement for active directory to work?
DNS is extremely important to all aspects of proper Active Directory operation. Any time a client makes a request for a domain service, it must find a domain controller to service that request, which is where DNS comes in to play.
There are two types of DNS queries: recursive and iterative.
When a DNS client requests DNS information, it uses a recursive query to do so.
In a recursive query, the DNS client sends its query to the first DNS server that it has been configured for in its TCP/IP configuration. It then sits and waits for the server to return an answer. If the server returns a positive response, the client will then go to the IP address returned by the server.
What is the name of the first domain in an Active Directory tree?
The first is the parent domain, and everything after that is a child domain. So you might have something like.
parent.local this would be the first domain of the parent domain
child.parent.local is the second or child domain
B). Delegation of Control Wizard
What can you do to promote a server to DC if you are on a remote location with slow WAN link?
First available in Windows 2003, you will create a copy of the system state from an existing DC and copy it to the new remote server. Run "Dcpromo /adv". You will be prompted for the location of the system state files
===================================
Answer B:
Backup system state as;
- Click Start, click Run, type ntbackup, and then click OK. (If the Backup utility starts in wizard mode, click the Advanced Mode hyperlink.)
- From the Backup tab, click to select the System State check box in the left pane. Do not back up the file system part of the SYSVOL tree separately from the system state backup.
- In the Backup media or file name box, specify the drive, path, and file name of the system state backup.
Restore system stat as below on the target computer;
- Log on to the Windows Server 2003-based computer that you want to promote. You must be a member of the local administrators group on this computer.
- Click Start, click Run, type ntbackup, and then click OK. (If the Backup utility starts in wizard mode, click the Advanced Mode hyperlink.)
- In the Backup utility, click the Restore and Manage Media tab. In the Tools menu, click Catalog a backup file..., and then locate the .bkf file that you created earlier. Click OK.
- Expand the contents of the .bkf file, and then click to select the System State check box.
- In Restore files to:, click Alternate Location. To restore the system state, type the logical drive and the path. We suggest that you type X:\Ntdsrestore. In this command, X is the logical drive that will ultimately host the Active Directory database when the member computer is promoted. The final location for the Active Directory database is selected when you run the Active Directory Installation Wizard. This folder must be different from the folder that contains the restored system state.
- Verify that the domain controller that is to be promoted has DNS name resolution and network connectivity to existing domain controllers in the domain controller's target domain.
- Click Start, click Run, type dcpromo /adv, and then click OK.
- Click Next to bypass the Welcome to the Active Directory Installation Wizard and Operating System Compatibility dialog boxes.
- On the Domain Controller Type page, click Additional domain controller for an existing domain, and then click Next.
- On the Copying Domain Information page, click From these restored backup files:, and then type the logical drive and the path of the alternative location where the system state backup was restored. Click Next.
- In Network Credentials, type the user name, the password, and the domain name of an account that is a member of the domain administrators group for the domain that you are promoting in.
- Continue with the remainder of the Active Directory Installation Wizard pages as you would with the standard promotion of an additional domain controller.
- After the SYSVOL tree has replicated in, and the SYSVOL share exists, delete any remaining restored system files and folders.
Rizwan Ranjha
Network Engineer
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