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DNS is the domain name binding with ip address. Every website on internet is recognized by the ip-address of the server on which it is running. Domain name is the human readable form so that we can easily remember and recognize a website. When this lookup of domain name to ip address fails then we get “temporary failure in name resolution” error.
In this article we will understand the basics of registry file and how we can resolve this error.
Before looking for a solution of any error it is important to know it’s root cause. In Linux, the DNS lookup is done through a special file which holds the nameserver entry. This file is located at
In this section we will see all the important terms we are going to use to solve this issue.
systemd-resolved– It is a system service. Local applications refer this service for network resolution. This service is responsible for all the name resolutions.
resolv.conf– This file provides a local DNS stub listener. Meaning, a local application can use the loop back interface IP address defined in this file to connect to
To know more about them, please refer to Ubuntu Documentation.
This error is not only confined to the wrong configuration in
resolv.conf file, else the reasons could be multiple. Let’s see some of the known culprits and their solutions.
Solution 1: If no nameserver entry in
This is the major reason for temporary failure in name resolution error. What happens is that due to some unexpected activity, either this file gets deleted or the nameserver entry gets erased.
So you need to check if there is a valid nameserver entry in this file.
/etc/resolv.conf file –
sudo vim /etc/resolv.conf
The file content should look like this –
# This file is managed by man:systemd-resolved(8). Do not edit. # # This is a dynamic resolv.conf file for connecting local clients to the # internal DNS stub resolver of systemd-resolved. This file lists all # configured search domains. # # Run "resolvectl status" to see details about the uplink DNS servers # currently in use. # # Third party programs must not access this file directly, but only through the # symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way, # replace this symlink by a static file or a different symlink. # # See man:systemd-resolved.service(8) for details about the supported modes of # operation for /etc/resolv.conf. nameserver 127.0.0.53 options edns0 trust-ad search rxwxpm3oahuuver0qduavec4jh.bx.internal.cloudapp.net
At the 17th line you can see the nameserver entry which is pointing to 127.0.0.53. This is the local loopback address used to listen DNS requests. You need to have this entry. Or, you can directly use the public DNS server of Google pointing at 220.127.116.11. Like this –
After making these changes and saving the file, you can restart
systemd-resolved service using this command –
sudo systemctl restart systemd-resolved.service
Solution 2: If updating nameserver in
If system is not allowing you to update nameserver entry in
/etc/resolv.conf file then you need to disable and stop
systemd-resolved service first. Follow these steps –
systemd-resolved service –
sudo systemctl disable systemd-resolved.service
Stop systemd-resolved service –
sudo systemctl stop systemd-resolved.service
Create Backup of resolv.conf file
sudo cp /etc/resolv.conf /etc/resolv.conf.backup
Remove Current resolv.conf file
sudo rm /etc/resolv.conf
Create New resolv.conf file and add Nameserver entry
sudo vim /etc/resolv.conf
Or, for Ubuntu you can use 127.0.0.53
systemd-resolved service –
sudo systemctl start systemd-resolved.service
Solution 3: If file permissions on
resolv.conf are wrong
There could be a possibility that some malicious program has changed the ownership of
resolv.conf file from root to something else. Follow these steps –
Set the owner to root using chown command –
sudo chown root:root /etc/resolv.conf
Set file permission to 644 –
sudo chmod 644 /etc/resolv.conf
Now check the permission and owner using
ls -la command –
ls -la /etc/resolv.conf
On my system it looks like this –
Solution 4: Blocked ports for Whois lookup and domain name resolution
Whois is the central directory of information of all the domains on internet. It is required to gather the details of any domain name like its nameservers, organization, contacts etc.
Port 43 is dedicated for Whois lookup.
Port 53 is used for domain name resolution
Both of these ports are essential for name resolution and need to be opened.
For Ubuntu & Debian Users –
These flavors of linux operating system uses
ufw firewall utility. To enable port 43 and 53, use this command –
sudo ufw allow 53/tcp sudo ufw allow 43/tcp sudo ufw reload
For CentOS & Fedora Users –
OS like CentOS and Fedora uses
firewalld utility hence their commands are different from debian. Use these commands –
sudo firewall-cmd --add-port=53/tcp --permanent sudo firewall-cmd --add-port=43/tcp --permanent sudo firewall-cmd --reload
“Temporary failure in name resolution” is a DNS lookup error where system is unable to access a valid IP address of a domain. You can encounter this error during a ping to a website. In this article we saw the various reasons for this error and resolved them one by one.