TCP/IP Configuration and Management Manual

Configuration Reference
TCP/IP Configuration and Management Manual—427132-004
A-14
Domain Name Server Files
In this example, the machine curly has two addresses (128.32.0.7 and 128.32.130.6).
The machine type is an HP 9000 Model 750, running HPUX that has timed and TFTP
services over UDP, and ECHO, TELNET, FTP, FINGER, and SMTP services over TCP.
These entries should be refreshed every hour (3600 seconds). They expire in 1000
hours (3600000 seconds). This refresh time and expiration time is given to the other
systems (such as secondary domain name servers). Secondary domain name servers
use this information to periodically update their databases.
DNSREV (Reverse Address-to-Name Mapping)
The DNSREV file shows the file responsible for the address-to-name mapping.
An example of the DNSREV file is:
;
;
@ IN SOA jiffy.kentcomm.com. joe.tardy.KCI.COM. (
1.1 ; Serial
3600 ; Refresh
300 ; Retry
3600000 ; Expire
3600 ) ; Minimum
IN NS pubs.kentcomm.com.
IN NS jiffy.kentcomm.com
6.0 IN PTR fred.kentcomm.com.
11.0 IN PTR jiffy.kentcomm.com.
14.0 IN PTR pubs.kentcomm.com.
6.130 IN PTR wilma.kentcomm.com.
Assume in the example, this is the database for the domain 33.128.IN-ADDR.ARPA.
Here, the address 128.33.0.14 would translate to pubs.kentcomm.com. The address
128.33.130.6 would translate to wilma.kentcomm.com.
Standard Resource Record Format
The records in the domain-name server data files are called resource records. The
Standard Resource Record Format is specified in RFC 882 and RFC 973. Also, see
DNS and BIND by Paul Albitz and Cricket Liu for a more information about this topic.
Resource records have a standard format, as follows:
[name] [ttl] addr-class record-type record-specific-data
The first field name is always the name of the domain record, and it always starts in
column 1. If you omit name, the resource record takes on the name of the previous
resource record.
The second field ttl is an optional time-to-live field. This field specifies how long (in
seconds) this data should be stored-in the by the resolver. By leaving this field blank,
the default time-to-live is specified in the Start of Authority resource record (see below).