Applies To: Windows Server 2008, Windows Server 2008 R2 In most Domain Name System (DNS) lookups, clients typically perform a forward lookup, which is a search that is based on the DNS name of another computer as it is stored in a host (A) resource record.This type of query expects an IP address as the resource data for the answered response.
Note The configuration of pointer (PTR) resource records and reverse lookup zones for identifying hosts by reverse query is strictly an optional part of the DNS standard implementation.
You are not required to use reverse lookup zones, although for some networked applications, they are used to perform security checks.
The IP addresses of the DNS tree can be delegated to organizations as they are assigned a specific or limited set of IP addresses within the Internet-defined address classes.
Finally, the domain tree, as it is built into DNS, requires an additional resource record type—the pointer (PTR) resource record—to be defined.
The reverse query process follows these steps: Remember that, if the queried reverse name is not answerable from the DNS server, normal DNS resolution (either recursion or iteration) can be used to locate a DNS server that is authoritative for the reverse lookup zone and that contains the queried name.