How to Install DNS on a Linux Server: A Step-by-Step Guide

Himanshu Joshi Knowledgebase

DNS (Domain Name System) is the backbone of the internet, translating domain names example.com into IP addresses that computers can understand. Whether you’re setting up a DNS server for a website, a local network, or for improved DNS resolution, installing DNS on a Linux server can be a powerful way to enhance your network’s performance and control.

In this guide, you’ll learn how to install DNS on a Linux server using popular DNS software like BIND, dnsmasq, and Unbound.

What is DNS?

DNS on a Linux Server

Before diving into the installation process, let’s define DNS. DNS is a system that resolves human-readable domain names into machine-readable IP addresses. For example, when you type www.example.com in your browser, DNS translates it to an IP address like 192.0.2.1, allowing you to access the website.

Why Install DNS on a Linux Server?

Setting up your own DNS server has several benefits:

  • Improved Performance: A local DNS server can speed up resolution times for your network.
  • Custom Configuration: You can define specific DNS settings for your organization or website.
  • Increased Security: A local DNS server allows you to filter requests, block malicious sites, and implement DNSSEC for secure communications.
  • Cost-Effective: By hosting your own DNS server, you avoid reliance on third-party DNS services.

Now, let’s move on to the steps to install DNS on a Linux server.

Prerequisites

Before you begin the installation, ensure the following:

  • A Linux Server: This could be any Linux distribution like Ubuntu, CentOS, or Debian.
  • Root or Sudo Privileges: You need administrative access to install and configure the DNS software.
  • Basic Networking Knowledge: DNS records (A, MX, CNAME, etc.) and IP addressing will help during configuration.
  • A Static IP Address: A static IP ensures your server’s address stays the same, which is important for DNS resolution.

Choose a DNS Software

There are a few different DNS server software options you can use on a Linux server. The three most popular options are BIND, dnsmasq, and Unbound. Let’s explore each briefly:

BIND (Berkeley Internet Name Domain)

BIND is the most widely used DNS server software and is ideal for both authoritative and recursive DNS setups. It is highly customizable and powerful, making it perfect for larger environments or those requiring full control over their DNS configurations.

dnsmasq

dnsmasq is a lightweight DNS server primarily used for local networks or smaller setups. It’s easy to configure and offers DNS caching, DHCP services, and DNS forwarding, making it a great choice for home networks or small businesses.

Unbound

Unbound is a validating, recursive DNS resolver known for its speed and security features. It is ideal if you need a secure DNS resolver with DNSSEC support and prefer a more minimalistic setup.

In this guide, we’ll focus on installing BIND, but the process is similar for dnsmasq and Unbound.

Install DNS Software

Now that you’ve chosen your DNS software, let’s move on to the installation. We’ll show you how to install DNS using BIND on Ubuntu/Debian. If you’re using a different Linux distribution, the commands may vary slightly.

Installing BIND (Primary DNS Server)

  • Update your package list:
sudo apt update
  • Install BIND9 (the DNS server software):
sudo apt install bind9
  • Enable BIND to start on boot:
sudo systemctl enable bind9sudo systemctl start bind9
  • Check if BIND is running:
sudo systemctl status bind9

Installing dnsmasq (Secondary or Local DNS Server)

For a smaller setup, dnsmasq may be more appropriate. Here’s how to install it:

  • Install dnsmasq:
sudo apt install dnsmasq
  • Start and enable dnsmasq:
sudo systemctl enable dnsmasqsudo systemctl start dnsmasq

Installing Unbound (Recursive DNS Resolver)

  • Install Unbound:
sudo apt install unbound
  • Start and enable Unbound:
sudo systemctl enable unboundsudo systemctl start unbound

Configuring the DNS Server

Now that the DNS software is installed, you need to configure it. Let’s start with the basics of configuring BIND.

Configuring BIND

  • Edit the main configuration file (/etc/bind/named.conf): Open the file for editing:
sudo nano /etc/bind/named.conf
  • Define DNS zones for domain names by adding zone files. For example, to set up a forward lookup zone, add the following to the named.conf file:
zone "example.com" { type master; file "/etc/bind/db.example.com"; };
  • Create the zone file (/etc/bind/db.example.com): The zone file maps domain names to IP addresses. Here’s an example:
$TTL 86400
@   IN  SOA  ns1.example.com. admin.example.com. (
        2021071001 ; Serial
        3600       ; Refresh
        1800       ; Retry
        1209600    ; Expire
        86400 )    ; Minimum TTL

@       IN  NS    ns1.example.com.
@       IN  A     192.0.2.1
www     IN  A     192.0.2.1

Configuring dnsmasq

  • Edit the dnsmasq.conf file:
sudo nano /etc/dnsmasq.conf
  • Set up basic configurations for local DNS and caching. For example:
server=8.8.8.8 no-resolv

This configuration tells dnsmasq to forward DNS queries to Google’s DNS servers (8.8.8.8) and avoid using the local resolver.

Configuring Unbound

  • Edit the Unbound configuration file (/etc/unbound/unbound.conf):
sudo nano /etc/unbound/unbound.conf
  • Basic Unbound configuration:
server:
    interface: 0.0.0.0
    access-control: 0.0.0.0/0 allow
    do-not-query-localhost: no

Setting Up DNS Zones

Once your DNS server is configured, you need to set up forward and reverse DNS zones.

Creating Forward Zones

Forward zones resolve domain names to IP addresses. You’ll define these in your zone files, as demonstrated above with example.com.

Creating Reverse Zones

Reverse zones map IP addresses back to domain names. For example, for 192.0.2.1, the reverse zone file would look something like this:

$TTL 86400
@   IN  SOA  ns1.example.com. admin.example.com. (
        2021071001 ; Serial
        3600       ; Refresh
        1800       ; Retry
        1209600    ; Expire
        86400 )    ; Minimum TTL

@   IN  PTR  example.com.

Testing the DNS Configuration

Once everything is configured, it’s time to test your DNS server:

  • Use dig or nslookup to test DNS resolution: For example, test the forward resolution:
dig example.com
  • Check logs for any issues: Logs are typically stored in /var/log/syslog or /var/log/messages, depending on your configuration.

Securing Your DNS Server

Securing your DNS server is crucial to avoid potential exploits.

  • Configure DNSSEC: Enable DNSSEC to validate DNS responses and protect against cache poisoning.
  • Limit access: Use access control to limit who can query your DNS server.
  • Regular updates: Keep your DNS software up-to-date with security patches.

Conclusion

You’ve learned how to install DNS on a Linux server. With your own DNS server, you gain control over domain name resolution, improve network performance, and enhance security. Remember to test your DNS configuration thoroughly, secure your server, and regularly monitor its performance to ensure optimal operation.

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