How To Set Permanent DNS Nameservers in Ubuntu and Debian
The /etc/resolv.conf is the main configuration file for the DNS name resolver library. The resolver is a set of functions in the C library that provide access to the Internet Domain Name System (DNS). The functions are configured to check entries in the /etc/hosts file, or several DNS name servers, or to use the host’s database of Network Information Service (NIS).
On modern Linux systems that use systemd (system and service manager), the DNS or name resolution services are provided to local applications via the systemd-resolved service. By default, this service has four different modes for handling the Domain name resolution and uses the systemd DNS stub file (/run/systemd/resolve/stub-resolv.conf) in the default mode of operation.
The DNS stub file contains the local stub 127.0.0.53 as the only DNS server, and it is redirected to the /etc/resolv.conf file which was used to add the name servers used by the system.
If you run the following ls command on the /etc/resolv.conf, you will see that this file is a symlink to the /run/systemd/resolve/stub-resolv.conf file.
$ ls -l /etc/resolv.conf lrwxrwxrwx 1 root root 39 Feb 15 2019 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf
Unfortunately, because the /etc/resolv.conf is indirectly managed by the systemd-resolved service, and in some cases by the network service (by using initscripts or NetworkManager), any changes made manually by a user can not be saved permanently or only last for a while.
In this article, we will show how to install and use the resolvconf program to set permanent DNS name servers in /etc/resolv.conf file under Debian and Ubuntu Linux distributions.
Why Would You Want to Ddit /etc/resolv.conf File?
The main reason could be because the systems DNS settings are misconfigured or you prefer to use specific name servers or your own. The following cat command shows the default name server in the /etc/resolv.conf file on my Ubuntu system.
$ cat /etc/resolv.conf
Check DNS Name Servers
In this case, when local applications such as the APT package manager try to access FQDNs (Fully Qualified Domain Names) on the local network, the result is a “Temporary failure in name resolution” error as shown in the next screenshot.
Temporary Failure Resolving
The same happens when you run a ping command.
$ ping google.com
Temporary Failure in Name Resolution
So when a user tries to manually set the name servers, the changes do not last for long or are revoked after a reboot. To resolve this, you can install and use the reolvconf utility to make the changes permanent.
To install the resolvconf package as shown in the next section, you need to first of all manually set the following name servers in the /etc/resolv.conf file, so that you access the FQDMs of Ubuntu repository servers on the internet.
nameserver 8.8.4.4 nameserver 8.8.8.8
Read Also: How to Setup Local DNS Using /etc/hosts File in Linux
Installing resolvconf in Ubuntu and Debian
First, update the system software packages and then install resolvconf from the official repositories by running the following commands.
$ sudo apt update $ sudo apt install resolvconf
Once the resolvconf installation is complete, systemd will trigger the resolvconf.service to be automatically started and enabled. To check if it is up and running issues the following command.
$ sudo systemctl status resolvconf.service
If the service is not started and enabled automatically for any reason, you can start and enable it as follows.
$ sudo systemctl start resolvconf.service $ sudo systemctl enable resolvconf.service $ sudo systemctl status resolvconf.service
Check Resolvconf Service Status
Set Permanent DNS Nameservers in Ubuntu and Debian
Next, open the /etc/resolvconf/resolv.conf.d/head configuration file.
$ sudo nano /etc/resolvconf/resolv.conf.d/head
and add the following lines in it:
nameserver 8.8.8.8 nameserver 8.8.4.4
Set Permanent DNS Name Servers in Resolvconf
Save the changes and restart the resolvconf.service or reboot the system.
$ sudo systemctl start resolvconf.service
Now when you check the /etc/resolv.conf file, the name server entries should be stored there permanently. Henceforth, you will not face any issues concerning name resolution on your system.
Permanent DNS Name Servers
I hope this quick article helped you in setting the permanent DNS nameservers in your Ubuntu and Debian systems. If you have any queries or suggestions, do share it with us in the comments section below.
Yet another systemd epic fail. It now takes a running service, and a management tool, to accomplish what was and should be a simple file edit.
@Walter
Any changes made manually by a user in the
/etc/resolv.conffile are not saved permanently or only last for a while. That’s the reason why we use the resolvconf utility or the method @Carlos Sousa has shared, to make changes permanent.Correct. But before systemd started overwriting resolv.conf, i.e., in every version of Linux and Unix between 1983 and 2014 all the way back to the first BSD that introduced IPv4 support (BSD 4.2), you could change your resolvers just by editing resolv.conf.
No daemon or utility is necessary. Systemd adds unnecessary complexity to a process that worked just fine for thirty years, all so that some crazy German can say “now we do it the same way as Apple!”
I always do:
@Carlos
True, this works as well but sets the file in an immutable state.