Resolvconf
In some FreeBSD, 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. Before a computer can connect to an external network resource by name, it must convert that alpha-numeric name (e.g., wikipedia.org) into its corresponding network address called an IP address (e.g., 66.230.200.10).