The named Files

The Ubuntu server places all of the configuration files needed for the named program in the /etc/bind folder. Table 20-6 shows these files and their purpose on the server.

Table 20-6: The Ubuntu named Files

File

Description

db.0

Zone file containing reverse lookup data for the network address

db.127

Zone file containing reverse lookup data for the localhost address

db.255

Zone file containing reverse lookup data for the broadcast address

db.empty

Blank zone file

db.local

Zone file for the local loopback address

db.root

Zone file containing information on root zone DNS servers

named.conf

The named master zone configuration file

named.conf.local

Zone configuration file for adding local zones

named.conf.options

Zone configuration file for adding named options

rndc.key

Encryption key file for communicating with remote DNS servers

zones.rfc1918

Zone file containing reverse lookup data for private network addresses

The named.conf configuration file is the master file that defines the zones recognized by the named service. It contains references to the other zone files, along with options files, so that the named program can incorporate all of the information into the configuration.

You may notice a trend to the DNS zone file-naming convention used by Ubuntu:

♦ named. files contain the zone hostname information.

♦ db. files contain reverse lookup data information.

The zones.rfc1918 file is a zone file that contains standard reverse lookup data for the special private network addresses defined in Request for Comments (RFC) 1918. If your local network uses a private network addressing scheme (such as 10.x.x.x or 192.168.x.x) you should include this file in your named.conf configuration.

Secret

DNS server configurations can get pretty messy, especially for large networks. Using separate files to contain different zone information is a great way to help organize information. The filename extension on the db. files is used by named to identify the first octet value in the IP address for the reverse lookup area. For example, the db.127 file contains the lines:

BIND reverse data file for local loopback interface $TTL 604800

@ IN SOA localhost. root.localhost. ( 1 ; Serial 604800 ; Refresh 86400 ; Retry continues

continued

2419200

; Expire

604800 )

; Negative Cache TTL

@ IN NS

localhost.

1.0.0 IN

PTR localhost.

This information defines a single PTR record for the 127.0.0.1 address (remember,

the IP octets are listed in reverse order in the PTR record). This defines the reverse

lookup for the special localhost IP address.

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