Resolv.conf is a computer file used by various operating systems as a DNS resolver. The file is in plain text. It’s usually generated by the system administrator or a network program. The file is located in the /etc/ directory and contains the search domain as well a list of nameservers.

Here’s an example of the /etc/resolv.conf file.

search domain.com local.lan
nameserver 1.1.1.1
nameserver 8.8.8.8
nameserver 9.9.9.9

If you have problems resolving domain names, check this file first.