How to Change DNS Server List in Linux

Proper DNS (Domain Name System) configuration is essential for reliable network connectivity on Linux systems. Adjusting the DNS server list can enhance speed, security, and the overall browsing experience. In this step-by-step guide, we’ll show you how to change the DNS server list in Linux efficiently, covering both legacy and modern configurations.

Table of Contents

1. Understanding DNS in Linux
2. Checking Current DNS Settings
3. Updating DNS in /etc/resolv.conf
4. Using systemd-resolved
5. Configuring DNS with NetworkManager
6. Netplan on Ubuntu Systems
7. Efficient Tips for Managing DNS
8. Conclusion

Understanding DNS in Linux

DNS translates domain names into IP addresses, enabling user-friendly browsing. Linux systems query DNS servers listed in configuration files or managed by services such as systemd-resolved or NetworkManager. Understanding how Linux determines which DNS servers to use is key to maintaining stable and efficient network operations.

Checking Current DNS Settings

Before making changes, it’s wise to know which DNS servers are currently in use. On most Linux distributions, you can inspect the DNS settings by viewing /etc/resolv.conf or using networking tools.

cat /etc/resolv.conf

This command displays the current nameservers your system is using.

Updating DNS in /etc/resolv.conf

The /etc/resolv.conf file traditionally holds DNS server entries. On many systems, this file is dynamically managed by other services. However, if you control it directly, you can edit it as follows:

sudo nano /etc/resolv.conf

Add or modify the nameserver lines:

nameserver 8.8.8.8
nameserver 1.1.1.1

Save and exit the editor. Changes are immediate but note that this file may be overwritten by network services on reboot. For persistent changes, integrate with your distribution’s network management tools or use chattr to make the file immutable (not recommended in most cases).

Using systemd-resolved

On systems with systemd-resolved, DNS configuration can be managed via the /etc/resolv.conf symlink or /etc/systemd/resolved.conf file:

sudo nano /etc/systemd/resolved.conf

Edit the configuration to specify DNS servers:

[Resolve]
DNS=8.8.8.8 1.1.1.1
FallbackDNS=8.8.4.4

Then restart the service:

sudo systemctl restart systemd-resolved

Configuring DNS with NetworkManager

NetworkManager can manage DNS settings for network interfaces. If you’re using a GUI, you can update DNS servers via Network Settings. For CLI-based configurations, use the nmcli command:

nmcli connection modify "Wired connection 1" ipv4.dns "8.8.8.8 1.1.1.1"
nmcli connection up "Wired connection 1"

This modifies the chosen connection’s DNS servers. Check the updated DNS list using:

nmcli device show | grep IP4.DNS

Netplan on Ubuntu Systems

Ubuntu uses netplan for network configuration. You can define DNS servers in .yaml files under /etc/netplan/:

sudo nano /etc/netplan/01-network-manager-all.yaml

Add DNS entries under the nameservers section:

network:
  version: 2
  renderer: NetworkManager
  ethernets:
    eth0:
      dhcp4: yes
      nameservers:
        addresses: [8.8.8.8, 1.1.1.1]

Apply the changes:

sudo netplan apply

Efficient Tips for Managing DNS

• Use a DNS Cache: Deploy tools like dnsmasq or unbound to cache DNS responses and speed up lookups.
• Monitor DNS Performance: Use commands like dig to test response times and ensure the DNS servers you’ve chosen are responsive.
• Automate with Scripts: If you frequently switch DNS servers (e.g., in different networks), consider using simple scripts or aliases to update your configuration quickly.
• Backup Configurations: Always back up your configuration files before making changes. This ensures you can revert if something goes wrong.

Conclusion

Changing DNS server lists in Linux can significantly improve your network’s performance and reliability. Whether you’re editing /etc/resolv.conf, leveraging systemd-resolved, or using advanced tools like NetworkManager or netplan, understanding the available methods is key. With the tips provided above, you can manage and optimize your DNS configurations efficiently.