Manage your Network!

Linux BIND DNS - Part 3: Configuring The db.192.168.0 Zone Data File

The db.192.168.0 zone data file is the second file we need to create and configure for our BIND DNS server. As outlined in the DNS-BIND Introduction, this file's purpose is to provide the IP Address -to- name mappings. Note that this file is to be placed on the Master DNS server for our domain.

Constructing The db.192.168.0 File

While we start to construct the file, you will notice many similarities with our previous file. Most resource records have already been covered and explained in our previous articles and therefore we will not repeat on this page.

The first line is our $TTL control statement, followed by the Start Of Authority (SOA) resource record:

$TTL 86400

0.168.192.in-addr.arpa. IN SOA voyager.firewall.cx. admin.firewall.cx. (

                     1 ; Serial
                 3h ; Refresh after 3 hours
                     1h ; Retry after 1 hour
                     1w ; Expire after one week
                     1h ) ; Negative Caching TTL of 1 hour

As you can see, everything above, except the first column of the first line, is identical to the db.firewall.cx file. The "0.168.192.in-addr.arpa" entry is our IP network in reverse order. The trick to figure out your own in-addr.arpa entry is to simply take your network address, reverse it, and add an ".in-addr.arpa." at the end

Name server resource records are next, follwed by the PTR resource record that creates our IP Address-to-name mappings. The syntax is nearly the same as the db.domain file, but keep in mind that we don't enter the full reversed IP Address for the name servers but only the first 3 octets which represent the network they belong to:

; Name Servers defined here
0.168.192.in-addr.arpa. IN NS voyager.firewall.cx.

0.168.192.in-addr.arpa. IN NS gateway.firewall.cx.

; IP Address to Name mappings
1.0.168.192.in-addr.arpa. IN PTR admin.firewall.cx.
5.0.168.192.in-addr.arpa. IN PTR enterprise.firewall.cx.
10.0.168.192.in-addr.arpa. IN PTR gateway.firewall.cx.
15.0.168.192.in-addr.arpa. IN PTR voyager.firewall.cx.

Time to look at the configuration file with all its entries:

$TTL 86400

0.168.192.in-addr.arpa. IN SOA voyager.firewall.cx. admin.firewall.cx. (

                     1 ; Serial
                 3h ; Refresh after 3 hours
                     1h ; Retry after 1 hour
                     1w ; Expire after one week
                     1h ) ; Negative Caching TTL of 1 hour

; Name Servers defined here
0.168.192.in-addr.arpa. IN NS voyager.firewall.cx.
0.168.192.in-addr.arpa. IN NS gateway.firewall.cx.

; IP Address to Name mappings
1.0.168.192.in-addr.arpa. IN PTR admin.firewall.cx.
5.0.168.192.in-addr.arpa. IN PTR enterprise.firewall.cx.
10.0.168.192.in-addr.arpa. IN PTR gateway.firewall.cx.
15.0.168.192.in-addr.arpa. IN PTR voyager.firewall.cx.

This completes the confgiuration of our db.192.168.0 Zone data file.

Remember the whole purpose of this file is to provide an IP Address-to-name mapping, which is why we do not use the domain name in front of each line, but the reversed IP Address followed by the in-addr.arpa. entry. Next article deals with the Common Files in Linux BIND DNS.