Why is dns a requirement for active directory to work?

Answer 1

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.

Answer 2

When you install Active Directory on a server, you promote the server to the role of a domain controller for a specified domain. When completing this process, you are prompted to specify a DNS domain name for the Active Directory domain for which you are joining and promoting the server.

If during this process, a DNS server authoritative for the domain that you specified either cannot be located on the network or does not support the DNS dynamic update protocol, you are prompted with the option to install a DNS server. This option is provided because a DNS server is required to locate this server or other domain controllers for members of an Active Directory domain.

Once you have installed Active Directory, you have two options for storing and replicating your zones when operating the DNS server at the new domain controller:

* Standard zone storage, using a text-based file.

Zones stored this way are located in .Dns 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 abc.com.dns if the zone name was "abc.com."

* Directory-integrated zone storage, using the Active Directory database.

Zones stored this way are located in the Active Directory tree under the domain or application directory partition. Each directory-integrated zone is stored in a dnsZone container object identified by the name you choose for the zone when creating it.

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.

* Zones are replicated and synchronized to new domain controllers automatically whenever a new one is added to an Active Directory domain.

Although DNS service can be selectively removed from a domain controller, directory-integrated zones are already stored at each domain controller, so zone storage and management is not an additional resource. Also, the methods used to synchronize directory-stored information offer performance improvement over standard zone update methods, which can potentially require transfer of the entire zone.

* By integrating storage of your DNS zone databases in Active Directory, you can streamline database replication planning for your network.

When your DNS namespace and Active Directory domains are stored and replicated separately, you need to plan and potentially administer each separately. For example, when using standard DNS zone storage and Active Directory together, you would need to design, implement, test, and maintain two different database replication topologies. For example, one replication topology is needed for replicating directory data between domain controllers, and another topology would be needed for replicating zone databases between DNS servers.

This can create additional administrative complexity for planning and designing your network and allowing for its eventual growth. By integrating DNS storage, you unify storage management and replication issues for both DNS and Active Directory, merging and viewing them together as a single administrative entity.

* 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.

Answer 3

When you install Active Directory on a server, you promote the server to the role of a domain controller for a specified domain. When completing this process, you are prompted to specify a DNS domain name for the Active Directory domain for which you are joining and promoting the server.

If during this process, a DNS server authoritative for the domain that you specified either cannot be located on the network or does not support the DNS dynamic update protocol, you are prompted with the option to install a DNS server. This option is provided because a DNS server is required to locate this server or other domain controllers for members of an Active Directory domain.

Once you have installed Active Directory, you have two options for storing and replicating your zones when operating the DNS server at the new domain controller:

* Standard zone storage, using a text-based file.

Zones stored this way are located in .Dns 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 abc.com.dns if the zone name was "abc.com."

* Directory-integrated zone storage, using the Active Directory database.

Zones stored this way are located in the Active Directory tree under the domain or application directory partition. Each directory-integrated zone is stored in a dnsZone container object identified by the name you choose for the zone when creating it.

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.

* Zones are replicated and synchronized to new domain controllers automatically whenever a new one is added to an Active Directory domain.

Although DNS service can be selectively removed from a domain controller, directory-integrated zones are already stored at each domain controller, so zone storage and management is not an additional resource. Also, the methods used to synchronize directory-stored information offer performance improvement over standard zone update methods, which can potentially require transfer of the entire zone.

* By integrating storage of your DNS zone databases in Active Directory, you can streamline database replication planning for your network.

When your DNS namespace and Active Directory domains are stored and replicated separately, you need to plan and potentially administer each separately. For example, when using standard DNS zone storage and Active Directory together, you would need to design, implement, test, and maintain two different database replication topologies. For example, one replication topology is needed for replicating directory data between domain controllers, and another topology would be needed for replicating zone databases between DNS servers.

This can create additional administrative complexity for planning and designing your network and allowing for its eventual growth. By integrating DNS storage, you unify storage management and replication issues for both DNS and Active Directory, merging and viewing them together as a single administrative entity.

* 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.

Answer 4

Dns is commonly used with AD for replication among domain controllers, as well as secure only updates to DNS.

Dns also helps map names to IP's so finding each other is much easier.