Windows Active Directory Interview Questions and Answers Part - 2

>What is the default size of ntds.dit ?
10 MB in Server 2000 and 12 MB in Server 2003 .

>Where is the AD database held and What are other folders related to AD ?
AD Database is saved in %systemroot%/ntds. You can see other files also in this folder. These are the main files controlling the AD structure.

ntds.dit
edb.log
res1.log
res2.log
edb.chk

When a change is made to the Win2K database, triggering a write operation, Win2K records the transaction in the log file (edb.log). Once written to the log file, the change is then written to the AD database. System performance determines how fast the system writes the data to the AD database from the log file. Any time the system is shut down, all transactions are saved to the database.

During the installation of AD, Windows creates two files: res1.log and res2.log. The initial size of each is 10MB. These files are used to ensure that changes can be written to disk should the system run out of free disk space. The checkpoint file (edb.chk) records transactions committed to the AD database (ntds.dit). During shutdown, a "shutdown" statement is written to the edb.chk file.

Then, during a reboot, AD determines that all transactions in the edb.log file have been committed to the AD database. If, for some reason, the edb.chk file doesn't exist on reboot or the shutdown statement isn't present, AD will use the edb.log file to update the AD database. The last file in our list of files to know is the AD database itself, ntds.dit. By default, the file is located in\NTDS, along with the other files we've discussed

>What FSMO placement considerations do you know of ?
Windows 2000/2003 Active Directory domains utilize a Single Operation Master method called FSMO (Flexible Single Master Operation), as described in Understanding FSMO Roles in Active Directory.

In most cases an administrator can keep the FSMO role holders (all 5 of them) in the same spot (or actually, on the same DC) as has been configured by the Active Directory installation process.

However, there are scenarios where an administrator would want to move one or more of the FSMO roles from the default holder DC to a different DC.
Windows Server 2003 Active Directory is a bit different than the Windows 2000 version when dealing with FSMO placement.

In this article I will only deal with Windows Server 2003 Active Directory, but you should bear in mind that most considerations are also true when planning Windows 2000 AD FSMO roles

>What do you do to install a new Windows 2003 R2 DC in a Windows 2003 AD?
If you're installing Windows 2003 R2 on an existing Windows 2003 server with SP1 installed, you require only the second R2 CD-ROM.

Insert the second CD and the r2auto.exe will display the Windows 2003 R2 Continue Setup screen. If you're installing R2 on a domain controller (DC), you must first upgrade the schema to the R2 version (this is a minor change and mostly related to the new Dfs replication engine).

To update the schema, run the Adprep utility, which you'll find in the Components\r2\adprep folder on the second CD-ROM.
Before running this command, ensure all DCs are running Windows 2003 or Windows 2000 with SP2 (or later).

Here's a sample execution of the Adprep /forestprep
command:
D:\CMPNENTS\R2\ADPREP>adprep /forestprep
ADPREP WARNING:
Before running adprep, all Windows 2000 domain controllers in the forest should be upgraded to Windows 2000 Service Pack 1 (SP1) with QFE 265089, or to Windows 2000 SP2 (or later).

QFE 265089 (included in Windows 2000 SP2 and later) is required to prevent potential domain controller corruption.
[User Action] If ALL your existing Windows 2000 domain controllers meet this requirement, type C and then press ENTER to continue. Otherwise, type any other key and press ENT ER to quit.
C Opened Connection to SAV

DALDC01 SSPI Bind succeeded Current Schema Version is 30 Upgrading schema to version 31 Connecting to "SAVDALDC01" Logging in as current user using SSPI Importing directory from file "C:\WINDOWS\system32\sch31.ldf" Loading entries... 139 entries modified successfully.

The command has completed successfully Adprep successfully updated the forest-wide information.
After running Adprep, install R2 by performing these steps:

1. Click the "Continue Windows Server 2003 R2 Setup" link, as the figureshows.
2. At the "Welcome to the Windows Server 2003 R2 Setup Wizard" screen, click Next.
3. You'll be prompted to enter an R2 CD key (this is different from your existing Windows 2003 keys) if the underlying OS wasn't installed from R2 media (e.g., a regular Windows 2003 SP1 installation).
Enter the R2 key and click Next. Note: The license key entered for R2 must match the underlying OS type, which means if you installed Windows 2003 using a volume-license version key, then you can't use a retail or Microsoft Developer Network (MSDN) R2 key.
4. You'll see the setup summary screen which confirms the actions to be performed (e.g., Copy files). Click Next.
5. After the installation is complete, you'll see a confirmation dialog box. Click Finish

>What is OU ?
Organization Unit is a container object in which you can keep objects such as user accounts, groups, computer, printer . applications and other (OU).
In organization unit you can assign specific permission to the user's. organization unit can also be used to create departmental limitation.

>Name some OU design considerations ?
OU design requires balancing requirements for delegating administrative rights - independent of Group Policy needs - and the need to scope the application of Group Policy.

The following OU design recommendations address delegation and scope issues:
Applying Group Policy An OU is the lowest-level Active Directory container to which you can assign Group Policy settings.
Delegating administrative authority
usually don't go more than 3 OU levels

>What is sites ? What are they used for ?
One or more well-connected (highly reliable and fast) TCP/IP subnets.
A site allows administrators to configure Active Directory access and replication topology to take advantage of the physical network.

A Site object in Active Directory represents a physical geographic location that hosts networks. Sites contain objects called Subnets.

Sites can be used to Assign Group Policy Objects, facilitate the discovery of resources, manage active directory replication, and manage network link traffic.
Sites can be linked to other Sites. Site-linked objects may be assigned a cost value that represents the speed, reliability, availability, or other real property of a physical resource. Site Links may also be assigned a schedule.

>Trying to look at the Schema, how can I do that ?
register schmmgmt.dll using this command
c:\windows\system32>regsvr32 schmmgmt.dll
Open mmc --> add snapin --> add Active directory schema
name it as schema.msc
Open administrative tool --> schema.msc

>What is the port no of Kerbrose ?
88

>What is the port no of Global catalog ? 
3268

>What is the port no of LDAP ?
389

>Explain Active Directory Schema ? 
Windows 2000 and Windows Server 2003 Active Directory uses a database set of rules called "Schema". The Schema is defines as the formal definition of all object classes, and the attributes that make up those object classes, that can be stored in the directory. As mentioned earlier, the Active Directory database includes a default Schema, which defines many object classes, such as users, groups, computers, domains, organizational units, and so on.

These objects are also known as "Classes". The Active Directory Schema can be dynamically extensible, meaning that you can modify the schema by defining new object types and their attributes and by defining new attributes for existing objects. You can do this either with the Schema Manager snap-in tool included with Windows 2000/2003 Server, or programmatically.

>How can you forcibly remove AD from a server, and what do you do later? ? Can I get user passwords from the AD database? 
Dcpromo /forceremoval , an administrator can forcibly remove Active Directory and roll back the system without having to contact or replicate any locally held changes to another DC in the forest. Reboot the server then After you use the dcpromo /forceremoval command, all the remaining metadata for the demoted DC is not deleted on the surviving domain controllers, and therefore you must manually remove it by using the NTDSUTIL command.

In the event that the NTDS Settings object is not removed correctly you can use the Ntdsutil.exe utility to manually remove the NTDS Settings object. You will need the following tool: Ntdsutil.exe, Active Directory Sites and Services, Active Directory Users and Computers

>What are the FSMO roles? Who has them by default? What happens when each one fails? 
Flexible Single Master Operation (FSMO) role. Currently there are five FSMO roles:
Schema master
Domain naming master
RID master
PDC emulator
Infrastructure master

>What is domain tree ? 
Domain Trees: A domain tree comprises several domains that share a common schema and configuration, forming a contiguous namespace. Domains in a tree are also linked together by trust relationships. Active Directory is a set of one or more trees.
Trees can be viewed two ways. One view is the trust relationships between domains. The other view is the namespace of the domain tree.

>What is forests ? 
A collection of one or more domain trees with a common schema and implicit trust relationships between them. This arrangement would be used if you have multiple root DNS addresses.

>How to Select the Appropriate Restore Method ?
You select the appropriate restore method by considering:
Circumstances and characteristics of the failure. The two major categories of failure, From an Active Directory perspective, are Active Directory data corruption and hardware failure.

Active Directory data corruption occurs when the directory contains corrupt data that has been replicated to all domain controllers or when a large portion of the Active Directory hierarchy has been changed accidentally (such as deletion of an OU) and this change has replicated to other domain controllers.

>Where are the Windows NT Primary Domain Controller (PDC) and its Backup Domain Controller (BDC) in Server 2003?
The Active Directory replaces them. Now all domain controllers share a multimaster peer-to-peer read and write relationship that hosts copies of the Active Directory.

>What is Global Catalog?
The Global Catalog authenticates network user logons and fields inquiries about objects across a forest or tree. Every domain has at least one GC that is hosted on a domain controller. In Windows 2000, there was typically one GC on every site in order to prevent user logon failures across the network.

>How long does it take for security changes to be replicated among the domain controllers?
Security-related modifications are replicated within a site immediately. These changes include account and individual user lockout policies, changes to password policies, changes to computer account passwords, and modifications to the Local Security Authority (LSA).

>When should you create a forest?
Organizations that operate on radically different bases may require separate trees with distinct namespaces. Unique trade or brand names often give rise to separate DNS identities. Organizations merge or are acquired and naming continuity is desired. Organizations form partnerships and joint ventures. While access to common resources is desired, a separately defined tree can enforce more direct administrative and security restrictions.

>Describe the process of working with an external domain name ?
If it is not possible for you to configure your internal domain as a subdomainof your external domain, use a stand-alone internal domain. This way, your internal and external domain names are unrelated. For example, an organization that uses the domain name contoso.com for their external namespace uses the name corp.internal for their internal namespace.

The advantage to this approach is that it provides you with a unique internal domain name. The disadvantage is that this configuration requires you to manage two separate namespaces. Also, using a stand-alone internal domain that is unrelated to your external domain might create confusion for users because the namespaces do not reflect a relationship between resources within and outside of your network.

In addition, you might have to register two DNS names with an Internet name authority if you want to make the internal domain publicly accessible.

>How do you view all the GCs in the forest?

C:\>repadmin /showreps
domain_controller

OR
You can use Replmon.exe for the same purpose.
OR
AD Sites and Services and nslookup gc._msdcs.

To find the in GC from the command line you can try using DSQUERY command.
dsquery server -isgc to find all the GC’s in the forest
you can try dsquery server -forest -isgc.

> What are the physical components of Active Directory ?

Domain controllers and Sites. Domain controllers are physical computers which is running Windows Server operating system and Active Directory data base. Sites are a network segment based on geographical location and which contains multiple domain controllers in each site.

> What are the logical components of Active Directory ?

Domains, Organizational Units, trees and forests are logical components of Active Directory.

> What are the Active Directory Partitions ?

Active Directory database is divided into different partitions such as Schema partition, Domain partition, and Configuration partition. Apart from these partitions, we can create Application partition based on the requirement.

> What is group nesting ?

Adding one group as a member of another group is called 'group nesting'. This will help for easy administration and reduced replication traffic.

> What is the feature of Domain Local Group ?

Domain local groups are mainly used for granting access to network resources.A Domain local group can contain accounts from any domain, global groups from any domain and universal groups from any domain. For example, if you want to grant permission to a printer located at Domain A, to 10 users from Domain B, then create a Global group in Domain B and add all 10 users into that Global group. Then, create a Domain local group at Domain A, and add Global group of Domain B to Domain local group of Domain A, then, add Domain local group of Domain A to the printer(of Domain A) security ACL.

>How will you take Active Directory backup ?

Active Directory is backed up along with System State data. System state data includes Local registry, COM+, Boot files, NTDS.DIT and SYSVOL folder. System state can be backed up either using Microsoft's default NTBACKUP tool or third party tools such as Symantech NetBackup, IBM Tivoli Storage Manager etc.

> What is Lost and Found Container ?

In multimaster replication method, replication conflicts can happen. Objects with replication conflicts will be stored in a container called 'Lost and Found' container. This container also used to store orphaned user accounts and other objects.

> Do we use clustering in Active Directory ? Why ?

No one installs Active Directory in a cluster. There is no need of clustering a domain controller. Because Active Directory provides total redundancy with two or more servers.

> What is Active Directory Recycle Bin ?

Active Directory Recycle bin is  a feature of Windows Server 2008 AD. It helps to restore accidentally deleted Active Directory objects without using a backed up AD database, rebooting domain controller or restarting any services.

> What is RODC ? Why do we configure RODC ?

Read only domain controller (RODC) is a feature of Windows Server 2008 Operating System. RODC is a read only copy of Active Directory database and it can be deployed in a remote branch office where physical security cannot be guaranteed. RODC provides more improved security and faster log on time for the branch office.

> How do you check currently forest and domain functional levels? Say both GUI and Command line.

To find out forest and domain functional levels in GUI mode, open ADUC, right click on the domain name and take properties. Both domain and forest functional levels will be listed there. TO find out forest and domain functional levels, you can use DSQUERY command.

> Which version of Kerberos is used for Windows 2000/2003 and 2008 Active Directory ?

All versions of Windows Server Active Directory use Kerberos 5.

> Name few port numbers related to Active Directory ?

Kerberos 88, LDAP 389, DNS 53, SMB 445

> What is an FQDN ?

FQDN can be expanded as Fully Qualified Domain Name.It is a hierarchy of a domain name system which points to a device in the domain at its left most end. For example in system.

> Have you heard of ADAC ?

ADAC- Active Directory Administrative Center is a new GUI tool came with Windows Server 2008 R2, which provides enhanced data management experience to the admin. ADAC helps administrators to perform common Active Directory object management task across multiple domains with the same ADAC instance.

> How many objects can be created in Active Directory? (both 2003 and 2008)

As per Microsoft, a single AD domain controller can create around 2.15 billion objects during its lifetime.

> explain the process between a user providing his Domain credential to his workstation and the desktop being loaded? Or how the AD authentication works ?

When a user enters a user name and password, the computer sends the user name to the KDC. The KDC contains a master database of unique long term keys for every principal in its realm. The KDC looks up the user's master key (KA), which is based on the user's password. The KDC then creates two items: a session key (SA) to share with the user and a Ticket-Granting Ticket (TGT). The TGT includes a second copy of the SA, the user name, and an expiration time. The KDC encrypts this ticket by using its own master key (KKDC), which only the KDC knows. The client computer receives the information from the KDC and runs the user's password through a one-way hashing function, which converts the password into the user's KA. The client computer now has a session key and a TGT so that it can securely communicate with the KDC. The client is now authenticated to the domain and is ready to access other resources in the domain by using the Kerberos protocol.

> What Is Urgent Replication And When Is It Used ?

You probably know how Active Directory core replication works. When there’s an object changed, the source DC, the one that serviced the change request, notifies it’s direct replication neighbours that there was a change to some object. The neighbors then start the replication process by requesting the changes made since the last replication.

Important to know is, that there is a “notification delay” between the actual change to the objects in the directory and the notification sent to the replication partners. Server 2003 DCs wait 15 seconds before they fire out the change notification. This delay is there to only send one change notification once the change transaction to the object is done. If there are multiple changes made to an object, let’s say the phone number, the home town and the employeeID of a user and the changes were made in 1 second delay each, we only send one change notification for those three changes. If there was no notification delay and we waited a second between the changes to a user’s attributes, the source DC were sending three change notifications to its partners. Too much traffic there! Note that the default change notificaction delay in Windows 2000 was 5 minutes (the numbers may differ depending on installation type (upgrade from 2000 to 2003, forest functional level, …).

Given that fact, one can think of several scenarios which may lead to “problem” since the change to the directory is not replicated right away: user Password changes, user lockout, Password Policy changed,…

For this reason, there’s urgent replication. Urgent replication works in the same way “normal” replication does, but has no notification delay of a few seconds/minutes. That makes “urgent” changes that need to be distributed thrughout the sites and DCs to get more quickly to all edges. Urgent replication takes place in the following cases:

• The Password Policy or account lockout policy of a domain has changed
• The LSA secret has changed (that’s used for the “secure channels” between machines and DCs and trusts)
• a user or computer is locked out due to a failed logon attempt (in this case, the urgent replication is used to notify the DC with the PDC emulator role first and then to all others)
• the RID master has changed

So — if one of the mentioned events take place, urgent replication takes place and there’s no notification delay prior to change notification of neighbour DCs.

> Which FSMO role directly impacting the consistency of Group Policy ?

PDC Emulator.

> I want to promote a new additional Domain Controller in an existing domain. Which are the groups I should be a member of ?

You should be a member of Enterprise Admins group or the Domain Admins group. Also you should be member of local Administrators group of the member server which you are going to promote as additional Domain Controller. 

> Tell me one easiest way to check all the 5 FSMO roles ?

Use netdom query /domain:YourDomain FSMO command. It will list all the FSMO role handling domain controllers. 

>What is Realm trust ? 
Use realm trusts to form a trust relationship between a non-Windows Kerberos realm and an Active Directory domain.

> Name few Active Directory Built in groups

• SID: S-1-5-32-544 - Name: Administrators - Description: A built-in group. After the initial installation of the operating system, the only member of the group is the Administrator account. When a computer joins a domain, the Domain Admins group is added to the Administrators group. When a server becomes a domain controller, the Enterprise Admins group also is added to the Administrators group.
• SID: S-1-5-32-548 - Name: Account Operators - Description: A built-in group that exists only on domain controllers. By default, the group has no members. By default, Account Operators have permission to create, modify, and delete accounts for users, groups, and computers in all containers and organizational units of Active Directory except the Builtin container and the Domain Controllers OU. Account Operators do not have permission to modify the Administrators and Domain Admins groups, nor do they have permission to modify the accounts for members of those groups.
• SID: S-1-5-32-549 - Name: Server Operators - Description: A built-in group that exists only on domain controllers. By default, the group has no members. Server Operators can log on to a server interactively; create and delete network shares; start and stop services; back up and restore files; format the hard disk of the computer; and shut down the computer.
• SID: S-1-5-32-550 - Name: Print Operators - Description: A built-in group that exists only on domain controllers. By default, the only member is the Domain Users group. Print Operators can manage printers and document queues.
• SID: S-1-5-32-551 - Name: Backup Operators - Description: A built-in group. By default, the group has no members. Backup Operators can back up and restore all files on a computer, regardless of the permissions that protect those files. Backup Operators also can log on to the computer and shut it down.

In a domain environment these groups are present, and are used for administrative purposes.

• SID: S-1-5-21domain-512 - Name: Domain Admins - Description: A global group whose members are authorized to administer the domain. By default, the Domain Admins group is a member of the Administrators group on all computers that have joined a domain, including the domain controllers. Domain Admins is the default owner of any object that is created by any member of the group.
• SID: S-1-5-21root domain-518 - Name: Schema Admins - Description: A universal group in a native-mode domain; a global group in a mixed-mode domain. The group is authorized to make schema changes in Active Directory. By default, the only member of the group is the Administrator account for the forest root domain.
  • SID: S-1-5-21root domain-519 - Name: Enterprise Admins - Description: A universal group in a native-mode domain; a global group in a mixed-mode domain. The group is authorized to make forest-wide changes in Active Directory, such as adding child domains. By default, the only member of the group is the Administrator account for the forest root domain.
  • SID: S-1-5-21domain-520 - Name: Group Policy Creator Owners - Description: A global group that is authorized to create new Group Policy objects in Active Directory. By default, the only member of the group is Administrator.