DNS Sample Domain Zone file

This file (pri.example.com) is the standard sample zone file used throughout this Chapter and has the following characteristics. NOTE: Both externally visible (public) services and internal hosts are defined in this file.

1. Two name servers are used one internal (ns1) and one external (ns2) to the domain
2. The mail service is external to the domain (provided by a third party)
3. FTP and WWW services are provided by the same host
4. There are two hosts named bill and fred
5. The host addresses are all in the class C private address range 192.168.0.0 (a slightly artificial case)

The Resource Records are all defined separately.

$TTL	86400 ; 24 hours could have been written as 24h or 1d
$ORIGIN example.com.
@  1D  IN	 SOA ns1.example.com.	hostmaster.example.com. (
			      2002022401 ; serial
			      3H ; refresh
			      15 ; retry
			      1w ; expire
			      3h ; minimum
			     )
       IN  NS     ns1.example.com. ; in the domain
       IN  NS     ns2.smokeyjoe.com. ; external to domain
       IN  MX  10 mail.another.com. ; external mail provider
; server host definitions
ns1    IN  A      192.168.0.1  ;name server definition     
www    IN  A      192.168.0.2  ;web server definition
ftp    IN  CNAME  www.example.com.  ;ftp server definition
; non server domain hosts
bill   IN  A      192.168.0.3
fred   IN  A      192.168.0.4 

An alternate file including only hosts externally visible to the domain is also provided. The CNAME Resource Record allow the 'www' server to provide additional services. The associated reverse map zone file is provided.