TCP/IP Tutorial and Technical Overview - IBM Redbooks

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4.1.112.129.in-addr.arpa. IN PTR VM2 ;note 6
;
;Some mailboxes
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central 10 IN MX VM2.test.example. ;notes 7 and 8
;
;a second definition for the same mailbox, in case VM2 is down
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central 20 IN MX VM1.test.example.
waste 10 IN MX VM2.test.example.
Figure 12-11 Zone data for the name server, continued from Figure 12-10 on page 447
Notes for Figure 12-10 on page 447 and Figure 12-11:
1. The $origin statement sets the @ variable to the zone name
(test.example.). Domain names that do not end with a period are suffixed
with the zone name. Fully qualified domain names (those ending with a
period) are unaffected by the zone name.
2. Defines the name server for this zone.
3. Defines the Internet address of the name server for this zone.
4. Specifies well-known services for this host. These are expected to always
be available.
5. Gives information about the host.
6. Used for inverse mapping queries (see 12.1.6, “Mapping IP addresses to
domain names: Pointer queries” on page 430).
7. Will allow mail to be addressed to user@central.test.example.
8. See 15.1.2, “SMTP and the Domain Name System” on page 565 for the
use of these definitions.
448 TCP/IP Tutorial and Technical Overview