resolver

resolver – resolver configuration file

/etc/resolv.conf

The resolver configuration file contains information that is read by the resolver routines the first time they are invoked by a process.

resolv.conf is the name of a computer file used in various operating systems to configure the Domain Name System (DNS) resolver library

The resolv.conf file typically contains directives with the default search domain or domains; used for FQDN completion when no domain suffix is supplied as part of the query. It also contains a list of IP addresses of nameservers available to a host. It usually looks like:

search example.com
nameserver 172.16.1.254
It is also possible to specify multiples of each type. Here’s an example resolv.conf file with multiple search domains and multiple name servers:

search example.com local.lan
nameserver 172.16.1.254
nameserver 172.16.2.254
resolv.conf is usually located in the /etc directory of the file system. You may edit this file with your favorite text editor if the system’s IP addresses are statically assigned, however if you have any network interfaces that use DHCP, the resolvconf program is available to manage such operations in a conflict-free manner