Installing and Administering Internet Services

78 Chapter 3
Configuring and Administering the BIND Name Service
Configuring a Primary Master Name Server
db.127.0.0 contains the resource record that maps 127.0.0.1 to the
name of the loopback address, usually localhost. The
hosts_to_named program creates this file.
;name class type data
@ IN SOA rabbit.div.inc.com. root.moon.div.inc.com. (
1 ; Serial
10800 ; Refresh every 3 hours
3600 ; Retry every hour
604800 ; Expires after a week
86400 ) ; Minimum ttl of 1 day
@ IN NS rabbit.div.inc.com.
1 IN PTR localhost.
name The name of the subdomain. In data files, @ represents
the current origin. The current origin is the domain
configured in this file, according to the boot file. The
boot file says that the 0.0.127.in-addr.arpa
domain is configured in the db.127.0.0 file.
Therefore, every instance of @ in the db.127.0.0 file
represents 0.0.127.in-addr.arpa.
The current origin is also appended to names that do
not end with a dot. For example, the 1 in the PTR line
would be interpreted as 1.0.0.127.in-addr.arpa.
class The optional class field specifies the protocol group.
IN, for internet addresses, is the most common class.
type The SOA (start-of-authority) record designates the start
of a domain, and indicates that this server is
authoritative for the data in the domain.
The NS record designates a name server for the current
origin (0.0.127.in-addr.arpa).
PTR records are usually used to associate an address in
the in-addr.arpa domain with the canonical name of
a host. The PTR record in the example db.127.0.0 file
associates the name localhost with the address