DNS on Windows Server 2003, 3rd Edition

Creating a New Reverse-Mapping Zone

Zones like movie.edu handle mapping names to addresses using A records. But mapping addresses back to names—reverse mapping—is just as important. As you may recall from Chapter 2, a special portion of the namespace, the in-addr.arpa domain, is designated for reverse mapping. There’s one domain name in in-addr.arpa for every possible IP address, and PTR (pointer) records attached to a domain name provide the actual reverse mapping. Just think of a PTR record as the opposite of an A record.

So after we create movie.edu, we’re not done. Movie U. has two /24 networks, 192.249.249/24 and 192.253.253/24. We need to create the corresponding in-addr.arpa zones for reverse mapping with the DNS console: 249.249.192.in-addr.arpa and 253.253.192.in-addr.arpa.

The process for creating an in-addr.arpa zone is the same as that for creating any other zone. Select terminator in the left pane and choose Action → New Zone. Follow the prompts in the New Zone Wizard as we did earlier, except this time choose Reverse lookup zone in the third window. Figure 4-20 shows the fourth window of the New Zone Wizard when creating a reverse-mapping zone.

Figure 4-20. Specifying the network number or name of a reverse-mapping zone

We specified the network number (see the selected field), and the DNS console automatically calculated the zone name (see the grayed-out field). Click ...