Resolv.conf
resolv.conf is the name of a computer file used in various operating systems to configure the Domain Name System (DNS) resolver library. The file is a plain-text file usually created by the network administrator or by applications that manage the configuration tasks of the system. The resolvconf program is one such program on FreeBSD or other Unix machines which manages the resolv.conf file.
Purpose
In most Unix-like operating systems and others that implement the BIND Domain Name System (DNS) resolver library, the resolv.conf configuration file contains information that determines the operational parameters of the DNS resolver. The DNS resolver allows applications running in the operating system to translate human-friendly domain names into the numeric IP addresses that are required for access to resources on the local area network or the Internet. The process of determining IP addresses from domain names is called resolving.
Contents and location
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.
See also
- Hosts (file)
- nsswitch.conf