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 126.96.36.199 nameserver 188.8.131.52 nameserver 184.108.40.206
If you have problems resolving domain names, check this file first.