We pick l.root-servers.net, one of the 13 root servers (1), and ask it about 73.121.98.79.in-addr.arpa and learn that in-addr.arpa is delegated to six name servers (2), so we ask d.in-addr-servers.arpa where we learn that 79.in-addr.arpa is delegated to six name servers, including ns3.nic.fr (3), so we ask that one and get the following answer:
