How to Set Up a DNS Server on Linux with BIND

How to Set Up a DNS Server on Linux with BIND

The Domain Name System (DNS) acts as the phonebook of the internet, translating human-readable domain names into machine-readable IP addresses.

On Linux systems, the most widely used DNS server implementation is BIND (Berkeley Internet Name Domain). It provides a powerful and flexible platform for running authoritative or recursive DNS services.

This guide walks through the complete process of installing and configuring a DNS server using BIND on Linux.

📦 Installing BIND on Linux

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Begin by installing the BIND server and its supporting utilities.

sudo yum install bind bind-utils

These packages include:

• named – the BIND DNS server daemon
• dig / nslookup tools – utilities for testing DNS queries
• Configuration templates for DNS zones

After installation, configuration files are typically located under:

/etc/named.conf
/var/named/

⚙️ Configuring the Primary DNS Server

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The main BIND configuration file is located at:

/etc/named.conf

This file controls server behavior, including network interfaces, query permissions, and DNS zone definitions.

Example configuration:

options {
 listen-on port 53 { any; };  // Listen on all network interfaces
 allow-query { any; };        // Allow DNS queries from any source
 recursion yes;               // Enable recursive queries
};

// Forward lookup zone
zone "example.com" IN {
 type master;
 file "/var/named/example.com.zone";
 allow-update { none; };
};

Key configuration points:

• listen-on determines which interfaces accept DNS requests.
• allow-query defines which clients may query the server.
• recursion enables recursive DNS lookups.

The zone block defines an authoritative DNS zone for your domain.

📄 Creating the Forward Zone File

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The forward zone file contains the DNS records that map domain names to IP addresses.

Create the file:

/var/named/example.com.zone

Example zone configuration:

$TTL 86400
@ IN SOA ns1.example.com. root.example.com. (
           2018010101 ; Serial (YYYYMMDDNN)
           3600       ; Refresh
           1800       ; Retry
           604800     ; Expire
           86400      ; Minimum TTL
         )
@   IN NS ns1.example.com.
@   IN A  192.168.1.10
www IN A  192.168.1.20

Explanation of the records:

• SOA (Start of Authority) – Administrative metadata for the zone.
• NS record – Declares the authoritative nameserver.
• A record – Maps a hostname to an IPv4 address.

In this example:

• example.com resolves to 192.168.1.10
• www.example.com resolves to 192.168.1.20

🔄 Configuring Reverse DNS Lookup

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Reverse DNS translates IP addresses back into hostnames.

Add a reverse lookup zone to /etc/named.conf:

zone "1.168.192.in-addr.arpa" IN {
 type master;
 file "/var/named/1.168.192.zone";
 allow-update { none; };
};

Then create the reverse zone file:

/var/named/1.168.192.zone

Example configuration:

$TTL 86400
@ IN SOA ns1.example.com. root.example.com. (
           2018010101
           3600
           1800
           604800
           86400
         )
@  IN NS ns1.example.com.
10 IN PTR example.com.
20 IN PTR www.example.com.

PTR records map the last octet of the IP address:

• 192.168.1.10 → example.com
• 192.168.1.20 → www.example.com

Reverse DNS is often required for mail servers, security validation, and network diagnostics.

🔐 Configuring Firewall and DNS Services

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To allow DNS traffic, ensure port 53 (UDP/TCP) is open in the firewall.

# Allow DNS traffic
sudo firewall-cmd --add-service=dns --permanent
sudo firewall-cmd --reload

# Start BIND
sudo systemctl start named

# Enable auto-start at boot
sudo systemctl enable named

You can verify that the service is running:

systemctl status named

🌐 How DNS Resolution Works

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When a user enters www.example.com into a browser, a multi-step resolution process converts the domain into an IP address.

DNS Resolution Workflow

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1. Local Cache Check The operating system checks its DNS cache.

2. Recursive Resolver If the record is not cached, the request is sent to a recursive DNS server (usually provided by the ISP).

3. Root Name Server The resolver queries a root server to find the appropriate Top-Level Domain (TLD) server.

4. TLD Name Server The root server points to the .com TLD nameserver.

5. Authoritative Server The TLD server directs the resolver to the authoritative server responsible for example.com.

6. IP Address Retrieval The authoritative server returns the requested IP address.

7. Caching and Response The resolver caches the result for the duration defined by the TTL and returns the IP to the client.

This entire process typically completes in just a few milliseconds.

🧠 Key DNS Terminology

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🧾 Summary

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Setting up a DNS server using BIND involves several key steps:

• Installing the BIND server and utilities
• Configuring the main server configuration file
• Creating forward and reverse zone records
• Enabling firewall access and starting the service
• Understanding how recursive DNS resolution works

Once configured, your Linux server becomes an authoritative DNS provider capable of resolving domain names and supporting network infrastructure services.