Active Directory Interview Questions And Answers

"Active Directory is the directory service used in Windows 2000 Server and is the foundation of Windows 2000 distributed networks."

The core of Active Directory is a combination of an LDAP server and MIT Kerberos 5 KDC running on a Windows 2000 server acting as a domain controller that work as a unit to provide authentication ("Who are you?") and authorization ("What are you allowed to do?") information within a group of interlinked systems.

Above and beyond that, the LDAP "face" of this structure behaves as an enterprise-wide distributed database that not only contains Windows-specific information but can be extended to incorporate user-defined data as well.

The AD is held together by DNS, which is used not only to locate specific machines within the AD but also to locate which functions of the AD are running on which domain controllers.

The term "forest" is used to describe a collection of AD domains that share a single schema for the AD. All DC's in the forest share this schema and it is replicated in a hierarchical fashion among them. The preferred model for Windows 2000 AD is to have an organization use a single forest that spans an entire enterprise.

While not an administrative block by themselves, forests are a major boundary in that only limited communication is available between forests. For example, it is difficult for a user in one forest to access a resource in another forest.

It is very difficult to integrate forests at this time because of potential problems reconciling schema differences between two forests.

In Windows 2000, a domain defines both an administrative boundary and a security boundary for a collection of objects that are relevant to a specific group of users on a network. A domain is an administrative boundary because administrative privileges do not extend to other domains. It is a security boundary because each domain has a security policy that extends to all security accounts within the domain. Active Directory stores information about objects in one or more domains.

Domains can be organized into parent-child relationships to form a hierarchy. A parent domain is the domain directly superior in the hierarchy to one or more subordinate, or child, domains. A child domain also can be the parent of one or more child domains, as shown below.

OU's have many of the attributes of an NT 4 domain. However, instead of requiring server resources to create and support, they are a logical construct within the Active Directory so an OU does not have to support and maintain a domain controller.

OU's are created by an administrator of an AD domain and can be freely named (and renamed). The OU can then be populated objects of many types including computers, groups, printers, users and other sub-OU's.

The real power of an OU is that once it is established, the administrator of its "parent" can delegate administrative authority -- in total or in part -- to any user or group that is in the AD.

When this happens, the designated user/group gains complete administrative authority over all objects in their OU and thus has all of the rights and abilities that a Windows NT domain administrator would have as well as some new ones such as the ability to further segment their OU into sub-OU's and delegate authority over those sub-elements as they see fit.

Group Policy is one of the most exciting -- and potentially complex -- mechanisms that the Active Directory enables. Group policy allows a bundle of system and user settings (called a "Group Policy Object" or GPO) to be created by an administrator of a domain or OU and have it automatically pushed down to designated systems.

Group Policy can control everything from user interface settings such as screen background images to deep control settings in the client such as its TCP/IP configuration and authentication settings. There are currently over 500 controllable settings. Microsoft has provided some templates as well to provide a starting point for creating policy objects.

A significant advantage of group policy over the old NT-style policies is that the changes they make are reversed when the policy no longer applies to a system. In NT 4, once a policy was applied to a system, removing that policy did not by itself roll back the settings that it imposed on the client. With Windows 2000, when a specified policy no longer applies to a system it will revert to its previous state without administrative interference.

Multiple policies from different sources can be applied to the same object. For example, a domain might have one or more domain-wide policies that apply to all systems in the domain. Below that, systems in an OU can also have policy objects applied to it, and the OU can even be further divided into sub-OU's with their own policies.

This can create a very complex web of settings so administrators must be very careful when creating these multiple layers of policy to make sure the end result -- which is the union of all of the applicable policies with the "closest" policy taking priority in most cases -- is correct for that system. In addition, because Group policy is checked and applied during the system boot process for machine settings and again during logon for user settings, it is recommended that GPO's be applied to a computer from no more than five "layers" in the AD to keep reboot and/or login times from becoming unacceptably long.

The "empty root domain" is an AD design element that has become increasingly popular at organizations with decentralized IT authority such as universities.

The empty root domain acts as a placeholder for the root of Active Directory, and does not typically contain any users or resources that are not required to fulfill this roll [sic]. [...] Only those privileges that have tree or forest-wide scope are restricted to the empty root domain administrators. Departmental administrators can work independently of other departments.

This politically neutral root domain provides a central source of authority and policy enforcement, and provides a single schema and global catalog that allows users to find resources anywhere in the university/district/state system. Individual IT departments retain a significant degree of independence and can control their own users and resources without having to worry that actions by administrators in other departments will disrupt their domain.

Allows domain controllers running both Windows 2000 and earlier versions of Windows NT to co-exist in the domain. In mixed mode, the domain features from previous versions of Windows NT Server are still enabled, while some Windows 2000 features are disabled. Windows 2000 Server domains are installed in mixed mode by default. In mixed mode the domain may have Windows NT 4.0 backup domain controllers present. Nested groups are not supported in mixed mode.

When all the domain controllers in a given domain are running Windows 2000 Server. This mode allows organizations to take advantage of new Active Directory features such as Universal groups, nested group membership, and inter-domain group membership.

LDAP is the directory service protocol that is used to query and update AD. LDAP naming
paths are used to access AD objects and include the following:
• Distinguished names
• Relative Distinguished names

1. Windows Server, Advanced Server, Datacenter Server
2. Minimum Disk space of 200MB for AD and 50MB for log files
3. NTFS partition
4. TCP/IP Installed and Configured to use DNS
5. Administrative privilege for creating a domain in existing network

1. Verify SRV Resource Records
After AD is installed, the DC will register SRV records in DNS when it restarts. We can
check this using DNS MMC or nslookup command.
Using MMC
If the SRV records are registered, the following folders will be there in the domain
folder in Forward Lookup Zone.

• msdes
• sites
• tcp
• adp

Using nslookup
>nslookup
>ls –t SRV Domain
If the SRV records are properly created, they will be listed.

2. Verifying SYSVOL
If SYSVOL folder is not properly created data stores in SYSVOL such are scripts, GPO,
etc will not be replicated between DCs.
First verify the following folder structure is created in SYSVOL
Domain
Staging
Staging areas
Sysvol
Then verify necessary shares are created.
>net share
It should show two shares, NETLOGON and SYSVOL

3. Verifying Database and Log files
Make sure that the following files are there at %systemroot%ntds
Ntds.dit, Edb.*, Res*.log

The Active Directory schema is the set of definitions that defines the kinds of objects, and the
types of information about those objects, that can be stored in Active Directory. The
definitions are themselves stored as objects so that Active Directory can manage the schema
objects with the same object management operations used for managing the rest of the
objects in the directory.
There are two types of definitions in the schema: attributes and classes. Attributes and
classes are also referred to as schema objects or metadata.
Attributes are defined separately from classes. Each attribute is defined only once and can be
used in multiple classes. For example, the Description attribute is used in many classes, but is
defined once in the schema, assuring consistency.

The Lightweight Directory Access Protocol, or LDAP , is an application protocol for querying and modifying data using directory services running over TCP/IP

In an Active directory forest, the domain controller is a server that contains a writable copy of the Active Directory Database participates in Active directory replication and controls access to network resource.

An active directory is a directory structure used on Microsoft Windows based computers and servers to store information and data about networks and domains.

Maintains a secure channel between this computer and the domain controller for authenticating users and services. If this service is stopped, the computer may not authenticate users and services, and the domain controller cannot register DNS records."

Kerberos is a network authentication protocol. It is designed to provide strong authentication for client/server applications by using secret-key cryptography.

SMTP - 25,
POP3 - 110,
IMAP4 - 143,
RPC - 135,
LDAP - 389,
SSL - 443,
HTTP - 80,
RDP - 3389,
DNS - 53,
DHCP - 67,68,
FTP-21,
GC-3268,
Secure LDAP - 636,
Kerberos - 88,
NNTP - 119,
TFTP - 69,
SNMP - 161.

Scavenging will help you clean up old unused records in DNS.

%SystemRoot%\ntds\NTDS.DIT.
Edb*.log is the transaction log file. Each transaction file is 10 megabytes (MB). When Edb.log file is full, active directory renames it to Edbnnnnn.log, where nnnnn is an increasing number starts from 1.
Edb.chk is a checkpoint file which is use by database engine to track the data which is not yet written to the active directory database file. The checkpoint file act as a pointer that maintains the status between memory and database file on disk. It indicates the starting point in the log file from which the information must be recovered if a failure occurs.
Res1.log and Res2.log: These are reserved transaction log files. The amount of disk space that is reserved on a drive or folder for this log is 20 MB. This reserved disk space provides a sufficient space to shut down if all the other disk space is being used.

Windows 2003 must be running with SP2
Run adprep /forestprep
Run adprep /domainprep
Start the installation from Windows 2008 DVD
Domain level must be in Native Mode
Installation must be started from windows 2003 OS

AD Domain Services auditing, Fine-Grained Password Policies,Read-Only Domain Controllers,Restartable Active Directory Domain Services

Read only Domain Controller, organizations can easily deploy a domain controller in locations where physical security cannot be guaranteed.

The Sysvol folder on a Windows domain controller is used to replicate file-based data among domain controllers. %systemroot%\SYSVOL

90 minutes give or take.