Adding a resource record to a reverse lookup zone
Updated: May 9, 2008
Applies To: Windows Server 2008
Although a reverse lookup zone in Domain Name System (DNS) can contain other resource records, the most common resource records in a reverse lookup zone are the pointer (PTR) resource record and the alias (CNAME) resource record.
The pointer (PTR) resource record maps an IP address to a host name. When the DNS server receives a reverse lookup query, it locates the pointer (PTR) resource record that contains the IP address and it replies to the query with the corresponding host name. There are three ways that a pointer (PTR) resource record can be added to a reverse lookup zone:
- When a reverse lookup zone is configured to allow dynamic updates, DNS clients (and, in some cases, Dynamic Host Configuration Protocol (DHCP) servers) can add a pointer (PTR) resource record when a DNS client is assigned an IP address by a DHCP server.
- When you use the DNS Manager snap-in to add a host (A or AAAA) resource record, you can select an option to automatically add a matching pointer (PTR) resource record to the corresponding reverse lookup zone.
- You can add the pointer (PTR) resource record directly by using DNS Manager or the Dnscmd command-line tool.
The alias (CNAME) resource record is most commonly used in reverse lookup zones that contain delegated zones (subdomains) to support so-called “classless subnets.” The alias (CNAME) resource records are added to the parent zone to alias pointer (PTR) records in the delegated zone. See How to configure a subnetted reverse lookup zone on Windows NT, Windows 2000, or Windows Server 2003 and RFC 2317, "Classless IN-ADDR.ARPA delegation" for detailed instructions for using alias (CNAME) resource records in a reverse lookup zone.
To complete this task, you can perform the following procedures: