Step-by-Step Guide to Building a DNS Server on Linux

Overview

Domain Name System (DNS) translates human‑readable domain names into IP addresses, enabling users to access services without memorizing numeric addresses. This guide explains how to set up a DNS server on Linux, covering caching, recursive queries, and both forward and reverse lookups.

Prerequisites

Install the BIND package, disable the firewall and SELinux, and ensure the server has a static IP address.

yum install bind -y

Configure named.conf

Edit /etc/named.conf and set the global options.

options {
    listen-on port 53 { any; };
    listen-on-v6 port 53 { ::1; };
    directory "/var/named";
    dump-file "/var/named/data/cache_dump.db";
    statistics-file "/var/named/data/named_stats.txt";
    memstatistics-file "/var/named/data/named_mem_stats.txt";
    recursing-file "/var/named/data/named.recursing";
    secroots-file "/var/named/data/named.secroots";
    allow-query { any; };
};

Explanation of key options

listen-on port 53 { any; }: Accept DNS queries on the standard port from any IPv4 address.

listen-on-v6 port 53 { ::1; }: Accept queries on IPv6 loopback only.

directory "/var/named": Directory where zone files are stored.

allow-query { any; }: Permit any client to query the server.

Define forward zone

Create a forward zone for example.com:

zone "example.com" IN {
    type master;
    file "example.com.zone";
    allow-update { none; };
};

In example.com.zone add resource records:

example.com.    IN  NS  dns.example.com.
 dns            IN  A   192.168.180.188
 www            IN  A   192.168.180.189
 exam           IN  A   192.168.180.190
 ftp            IN  A   192.168.180.191
 sun            IN  A   192.168.180.44

Define reverse zone

Create a reverse zone for the 192.168.180.0/24 network:

zone "180.168.192.in-addr.arpa" IN {
    type master;
    file "example.com.arpa";
    allow-update { none; };
};

In example.com.arpa add PTR records:

@               IN  NS  dns.example.com.
188             IN  PTR dns.example.com.
189             IN  PTR www.example.com.
190             IN  PTR exam.example.com.
191             IN  PTR ftp.example.com.
44              IN  PTR sun.example.com.

Client configuration and testing

On a client machine, edit /etc/resolv.conf to point to the DNS server: nameserver 192.168.180.188 Test forward resolution: dig www.example.com Test reverse resolution:

dig -x 192.168.180.189

Common issues

If the named service fails to start, verify the configuration syntax: named-checkconf /etc/named.conf Check the service status and logs with systemctl status named and journalctl -xe. Ensure all zone files end with a trailing dot and that the files referenced in named.conf exist.