How to Specify a Master Server

The two types of master server are as follows.

• Zone master server. Each zone has one server that is designated as the master master server for that zone. A zone's master master server is the authoritative server for that zone.

• Zone slave server. A zone can have one or more slave master servers. Slave master servers obtain their DNS data from the zone's master server.

To specify a server as the master server for a given zone, you create three master records in that server's named.boot file.

1. Create the master record for the zone.

   This record designates the server as a master server for the zone and tells the server where to find the authoritative hosts file. A “master” record has three fields.

   • The first field designates the server as master.

   • The second field identifies the zone the master serves.

   • The third field identifies the hosts file.

   For example, the following line in a boot file specifies that the server is the master server for the doc.com zone, using authoritative data from the file db.doc.

   master doc.com db.doc

2. Create a master record for the zone's reverse map.

   This record designates the server as a master server for the zone's reverse address map, that is, the reverse address domain for doc.com. The record also tells the server where to find the authoritative hosts file. This record has three fields. The first field designates the server as master, the second field identifies the zone, and the third field identifies the hosts.rev file.

   The reverse address domain for a zone contains the zone's IP address in reverse order followed by in-addr.arpa. For example, suppose that the doc.com zone's IP address is 10.0.0. In that case, the reverse address domain would be 0.0.10.in-addr.arpa.

   Thus, the following line in a boot file specifies that the server is the master server for the reverse address domain of the doc.com zone, using authoritative data from the file doc.rev.

   master 0.0.10.in-addr.arpa doc.rev

3. Create a master record for the reverse address of the local loopback interface or host.

   This record designates the server as a master server for the loopback host, and tells the server where to find the authoritative hosts file. This record has three fields, the first field designates the server as master, the second field identifies the loopback host reverse address, and the third field identifies the hosts file.

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   Note –

   Loopback hosts are always identified as 0.0.10.in-addr.arpa.

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   Thus, the following line in a boot file specifies that the server is the master server for the reverse address domain of the loopback host using authoritative data from the file named.local.

   master 0.0.10.in-addr.arpa named.local