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Archive for March, 2008

Active Directory Services

Posted by Milind Naphade on 28/03/2008

It was very busy time since past few days so it was very hard for me to take out some time post a new item here on the blog. Now, everything seems to be settled down and things are going very fine on my servers.
This post is going to cover the below mentioned key points today. Anything you feel is missing from the blog or can be made better please write your comments to me directly at

Ok now, lets understand the what active directory is and how it evolved.

International Telecommunication Union (ITU) is a United Nations agency that plays a role as a forum for governments that want to achieve consensus on global telecom issues. Several manufacturers and service providers among more than 130 countries across the globe are members of ITU.

The branch of the ITU specifically tasked with making directory service recommendations is the Telecommunication Standardization Sector, or ITU-T. The ITU-T was formerly known as Comité Consultatif International Téléphonique et Télégraphique (CCITT).

The ITU-T recommends in many areas, from broadcast requirements and measuring equipment to faxing. These recommendations are grouped into lettered series. For example, the V series covers data communication over telephone networks and includes such famous standards such as V.34, “Wideband Analog Modem Communication,” and V.90, “Connecting Analog to Digital Modems.”

The X series of recommendations, which includes the X.500 recommendations for directory services, covers a variety of data network and open system communication technologies, such as X. 25 packet-switched networks and X.400 messaging systems. All these recommendations issued by ITU-T can be found at

Initially, Microsoft introduced directory services in its first ever and most stable operating system; very well known as Windows NT 4.0 This operating system lasted a very long time in the market and on the corporate networks. The domain services provided by Windows NT 4.0 started dominating Novell’s directory services. Slowly, it grabbed the market and Novell remained on the networks wherever it was implemented before. Off course no one would like to go for the black and white and non user friendly interfaces if he/she is provided a good looking and easy to use graphical user interface which made the tasks simpler for administrators and utilization of resources for the end users.

As the networks started growing rapidly the requirement of manageability, scalability and functionality of Windows NT 4.0 started decreasing. It resulted in the rise of new directory service named as Active Directory. Microsoft added some salient features in Active Directory services those offered more reliable structure of directory services. Firstly, it was introduced with the Windows 2000 Server version. Following are the features implemented in Microsoft Windows Server 2003.

Site scalability. The calculations for determining replication topology between sites have been streamlined. This corrects a problem where large organizations with hundreds of sites might experience replication failure because the topology calculations cannot be completed in the time allotted to them.
Backlink attribute replication. Group members are now replicated as discrete entities instead of replicating the entire group membership list as a single unit. This corrects a problem where membership changes made to the same group on different domain controllers in the same replication interval overwrite each other.
Federations. A new trust type called Forest was added to simplify transitive trust relationships between root domains in different forests. Using Forest trusts, it is possible to build a federation of independent Active Directory forests. This feature does not implement true “prune and graft” in Active Directory, but it goes a long way toward simplifying operations within affiliated organizations.
Simplified domain logon. Universal group membership can be cached at non-global catalog servers. This permits users to log on even if connectivity to a global catalog server is lost. This enhancement is coupled with a feature in XP where the domain\name result of cracking a User Principal Name (UPN) is cached locally. This permits a user at an XP desktop to log on with the format even if a global catalog server is not available.
Application naming contexts. Windows Server 2003 introduces the capability to create new naming contexts to hold DNS record objects for Active Directory Integrated zones. One naming context holds domain zone records and one holds the _msdcs records used throughout a forest. These naming contexts make it possible to target replication of DNS zones only to domain controllers that are running DNS.
Eliminate piling onto new domain controllers. There is potential for a problem when an NT4 primary domain controller (PDC) is upgraded to Windows Server 2003. In this circumstance, all existing Windows 2000 and XP desktops will use the newly promoted PDC as a logon server. In Windows Server 2003, domain controllers can be configured to respond to modern Windows clients as if they were still classic NT domain controllers until sufficient domain controllers are available to handle local authentication. This feature is also available in Windows 2000 SP2 and later.
DNS diagnostics. Proper DNS configuration is critical for proper Active Directory operation. The Domain Controller promotion utility now performs a suite of DNS diagnostics to ensure that a suitable DNS server is available to register the service locator resource records associated with a Windows domain controller.
Fewer global catalog rebuilds. Adding or removing an attribute from the Global Catalog no longer requires a complete synchronization cycle. This minimizes the replication traffic caused by adding an attribute to the GC.
Management console enhancements. The Active Directory Users and Computers console now permits drag-and-drop move operations and modifying properties on multiple objects at the same time. There is also the capability of creating and storing custom LDAP queries to simplify managing large numbers of objects. The new MMC 2. 0 console includes scripting support that can eliminate the need to use the console entirely.
Real-time LDAP. Support was added for RFC 2589, “LDAPv3: Extensions for Dynamic Directory Services.” This permits putting time-sensitive information in Active Directory, such as a user’s current location. Dynamic entries automatically time out and are deleted if they are not refreshed.
Enhanced LDAP security. Support was added for digest authentication as described in RFC 2829, “Authentication Methods for LDAP.” This makes it easier to integrate Active Directory into non-Windows environments. Support was also added for RFC 2830, “LDAPv3: Extension for Transport Layer Security.” This permits using secure connections when sending LDAP (Lightweight Directory Access Protocol) queries to a domain controller.
Schema enhancements. The ability was added to associate an auxiliary schema class to individual objects rather than to an entire class of objects. This association can be dynamic, making it possible to temporarily assign new attributes to a specific object or objects. Attributes and object classes can also be declared defunct to simplify recovering from programming errors.
LDAP query enhancements. The LDAP search mechanism was expanded to permit searching for individual entries in a multivalued Distinguished Name (DN) attribute. This is called an Attribute Scoped Query, or ASQ. For example, an ASQ could be used to quickly list every group to which a specific user belongs. Support was also ad

ded for Virtual List Views, a new LDAP control that permits large data sets to be viewed in order instead of paging through a random set of information. This change permits Windows Server 2003 to show alphabetically sorted lists of users and groups in pick lists.
Interoperability. This enhances interoperability with Netscape and NetWare directory services, both of which use the inetOrgPerson object class to create User objects.
Speedier domain controller promotions. The capability was added for using a tape backup of the Active Directory database to populate the database on a new domain controller. This greatly simplifies domain controller deployments in situations where it is not practical to ship an entire server.
Scalability. The maximum number of objects that can be stored in Active Directory was increased to over one billion.

These were the enhancements made in the recent release of Windows, Microsoft Windows Server 2003 Active Directory Services. In the next posts I will be covering the remaining stuff related to Active Directory.

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