hosts - static table lookup for hostnames

/etc/hosts
# The following lines are desirable for IPv4 capable hosts
       127.0.0.1       localhost

       # 127.0.1.1 is often used for the FQDN of the machine
       127.0.1.1       thishost.example.org   thishost
       192.168.1.10    foo.example.org        foo
       192.168.1.13    bar.example.org        bar
       146.82.138.7    master.debian.org      master
       209.237.226.90  www.opensource.org

man hosts