We pick f.root-servers.net, one of the 13 root servers (1), and ask it about gx-in-f42.1e100.net and learn that net is delegated to 13 name servers (2), so we ask c.gtld-servers.net where we learn that 1e100.net is delegated to four name servers, including ns3.google.com (3), so we ask that one and get the following answer:
gx-in-f42.1e100.net has one IP number (74.125.65.42), which also has a corresponding reverse pointer. You might also be interested in similar looking domain names: gx-in-f41.1e100.net,...