NETWORKING=yes HOSTNAME=totosh.ampoliros.net GATEWAY=192.168.0.254
# DNS FDN nameserver 184.108.40.206 nameserver 220.127.116.11
This is about associating and IP address with a domain name. It usually depends on your access provider, since they provide you with an IP address.
My internet access provider for totosh is currently Free SAS. The reverse DNS setup is described at http://www.free.fr/assistance/248.html.
To check the rDNS:
$ host 18.104.22.168 22.214.171.124.in-addr.arpa domain name pointer totosh.ampoliros.net.