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Providing Reverse Lookup

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Applies To: Windows Server 2008

In most Domain Name System (DNS) lookups, clients typically perform a forward lookup, which is a search based on the DNS name of another computer as the name is stored in a host (A or AAAA) resource record. This type of query expects an IP address as the resource data for the answered response.

DNS also provides a reverse lookup process, in which clients use a known IP address during a name query and look up a computer name based on its address. A reverse lookup takes the form of a question, such as "Can you tell me the DNS name of the computer that uses the IP address 192.168.1.20?"

To provide this answer, two special domains, in-addr.arpa and ip6.arpa, are defined in the DNS standards and reserved in the Internet DNS namespace to support reverse queries. The in-addr.arpa domain provides reverse-lookup support for IP version 4 (IPv4)-based IP addresses, while the ip6.arpa domain provides reverse lookup for IP version 6 (IPv6)-based IP addresses.

To make it possible for DNS clients to perform a reverse lookup for a host, you perform two steps:

  1. Create a reverse lookup zone that corresponds to the subnet network address of the host.

  2. In the reverse lookup zone, add a pointer (PTR) resource record that maps the host IP address to the host name.

After you create the zone, you manage it much as you would a forward lookup zone. Also, like a forward lookup zone, a reverse lookup zone can be integrated with Active Directory Domain Services (AD DS), and it can be mirrored by secondary and stub zones. You can also delegate a reverse lookup zone, and you can configure a reverse lookup zone to accept dynamic updates, which reduces the need to add and manage pointer (PTR) resource records directly.

This section includes the following tasks for providing reverse lookup: