In some Linux distributions, and other Unix-like operating systems, the resolvconf program maintains the system information about the currently available name servers and manages the contents of the configuration file resolv.conf, which determines Domain Name System (DNS) resolver parameters.
When computer connects to the internet, the domain name must be convert to corresponding IP address. The Domain Name Server is responsible for this conversion by maintaining a list of domain names and corresponding IP address. The information about the servers is kept in the configuration file resolv.conf.
The resolv.conf file exist at location /etc/resolv.conf which is a symbolic link to /run/resolvconf/resolv.conf. When computer connects to internet, resolvconf gets the name-servers from DHCP and list in resolv.conf file. But sometimes this fails to happen.
One of the reason may be that you deliberately change /etc/resolv.conf file to fill name-servers manually. Now /etc/resolv.conf file is no more a symbolic link and resolvconf doesn’t update /etc/resolv.conf file. Now you find yourself in all problems related to resolv.conf.
The solution is to configure resolvconf again. Make a backup copy of resolv.conf and use the following command
sudo dpkg-reconfigure resolvconf
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