Chapter 5

DNS Administration (Reference)

This chapter covers the following topics.

Implementing DNS

A Practical Example

This section shows the files you need to implement DNS for a sample Internet-connected network, based on the examples used in this chapter.

Caution - The IP addresses and network numbers used in examples and code samples in this manual are for illustration purposes only. Do not use them as shown because they might have been assigned to an actual network or host.

This example assumes the following.

An environment connected to the Internet

Two networks, each with its own domain (doc.com and sales.doc.com) and its own DNS zone

The doc.com domain and zone is the top zone over the sales.doc.com subdomain and zone

Each network has its own network number

Table 5-1 Example Network Domain and Zone Configuration

Name and Zone	Number
`doc.com`	`123.45.6`
`sales.doc.com`	`111.22.3`

Each zone has a master and one slave server, and the slave server of sales.doc.com is also the master server of doc.com:

Table 5-2 Example Network DNS Servers

Zone	Host Name	Function	Address	CNAME
`doc.com`	`sirius`	master for `doc.com`	`123.45.6.1`	`dnsmaster`
`doc.com`	`deneb`	slave for `doc.com`	`111.22.3.5`	`dnssecond`
`sales.doc.com`	`altair`	`master` for `sales.doc.com`	`111.22.3.4`	`dnssales`
`sales.doc.com`	`altair`	slave for `sales.doc.com`	`123.45.6.1`	`dnsmaster`

Example Boot Files

The following code examples show boot files for the three servers in the two networks:

Example 5-1 Example Boot File for dnsmastr Server

; named.boot file on the dnsmastr (sirius)
; 
; files required by in.named are located here 
directory /var/named
; here are the names of the master files
cache         .                         named.ca
master       doc.com                   db.doc
master       0.0.127.in-addr.arpa      named.local
master       6.45.123.in-addr.arpa     doc.rev
;This system is also the slave for the sales.doc.com domain
slave     sales.doc.com             111.22.3.4   db.sales
slave     3.22.111.in-addr.arpa     111.22.3.4   sales.rev

Example 5-2 Example Boot File for dnssales Server

; named.boot file on the dnssales (altair)
; 
; in.named is located here
directory /var/named
; here are the names of the master files
cache      .                        named.ca
master    sales.doc.com            db.sales
master    0.0.127.in-addr.arpa     db.127.0.0
master    3.22.111.in-addr.arpa    db.192.168.8

Example 5-3 Example Boot File for dnssecond Server

; named.boot file on the dnsecond (deneb)
directory /var/named
cache           .               named.ca
slave       doc.com         123.45.6.1 doc.com
slave       6.45.123.in-addr.arpa    123.45.6.1 doc.123.45.6

Example `resolv.conf` Files

The following code examples show resolv.conf files for the three servers in the two networks. (If the host in question is not running in.named, the local host address should not be used as a name server.)

Example 5-4 Example resolve.conf File for dnsmastr Server

;
; /etc/resolv.conf file for dnsmaster (sirius)
;
domain           doc.com
nameserver       0.0.0.0
nameserver       111.22.3.5

Example 5-5 Example resolve.conf File for dnssales Server

;
; /etc/resolv.conf file for dnssales (altair)
;
domain           sales.doc.com
nameserver       111.22.3.4
nameserver       123.45.6.1

Example 5-6 Example resolve.conf File for dnssecond Server

;
; /etc/resolv.conf for dnssecond
;
domain           doc.com
nameserver       111.22.3.5
nameserver       123.45.6.1

DNS Administration (Reference)

Implementing DNS

A Practical Example

Example Boot Files

Example resolv.conf Files

Example `resolv.conf` Files