HP-UX IP Address and Client Management Administrator's Guide (October 2009)

Master Server db.net Files
A master server has one db.net file for each network it serves. net is the network number
specified with the -n option in the hosts_to_named command. This file must contain a PTR
record for every host in the zone. A PTR record allows BIND to translate an IP address into a
host name. BIND resolves the address of a name by tracing down the domain tree and contacting
a server for each label of the name.
The in-addr.arpa domain is created to allow this inverse mapping. The in-addr.arpa
domain is preceded by four labels corresponding to four bytes (octets) of an Internet address.
You must specify each byte even if it is zero. For example, the address 143.22.0.3 has the domain
name 3.0.22.143.in-addr.arpa. The four octets of the address are reversed.
;
; db.15.19.8
;
$TTL 86400
@ IN SOA rabbit.div.inc.com. root.moon.div.inc.com.(
1 ; Serial
10800 ; Refresh every 3 hours
3600 ; Retry every hour
604800 ; Expire after a week
86400) ; Minimum ttl of 1 day
IN NS rabbit.div.inc.com.
IN NS indigo.div.inc.com.
119 IN PTR rabbit.div.inc.com.
64 IN PTR cheetah.div.inc.com.
197 IN PTR indigo.div.inc.com.
The example file, db.15.19.8, contains the following records:
SOA Start of Authority record. The SOA record indicates that this server is authoritative for
the data in the domain.
The at sign (@) in the data file represents the current origin. The current origin is the
domain configured in this file, according to the configuration file /etc/named.conf.
The configuration file indicates that the 8.19.15.in-addr.arpa domain is configured
in the db.15.19.8 file. Therefore, every instance of @ in the db.15.19.8 file represents
8.19.15.in-addr.arpa.
The SOA record indicates the name of the host this data file was created on, an electronic
mailing address of the name server’s technical contact, and the following values:
Serial
Indicates the version number of this file, incremented whenever the
data is changed.
Refresh
Indicates (in seconds) how often a slave name server should try to
update its data from a master server.
Retry
Indicates (in seconds) how often a slave server should retry after an
attempted refresh fails.
Expire
Indicates (in seconds) how long the slave name server can use the
data before it expires for lack of a refresh.
Minimum ttl
Indicates the minimum number of seconds for the time to live field
on other resource records for this domain.
NS Name Server records. The NS records specifies the names of the name servers and the
domains for which the domain has authority. The domain for the name servers in the
example is the current origin (8.19.15.in-addr.arpa), because @ was the last domain
specified.
PTR Pointer records. PTR records are usually used to associate an address in the
in-addr.arpa domain with the canonical name of a host. The first PTR record in the
example file db.15.19.8 associates the name rabbit.div.inc.com with the address
Configuring a Master Name Server 75