We pick i.root-servers.net, one of the 13 root servers (1), and ask it about www.travel4arab.com and learn that com is delegated to 13 name servers (2), so we ask k.gtld-servers.net where we learn that travel4arab.com is delegated to five name servers, including ns2.yahoo.com (3), so we ask that one where we see a CNAME from www.travel4arab.com to travel4arab.com, so we have to start all over again. We already know that ns3.yahoo.com is authoritative for travel4arab.com (4) and ask it about travel4arab.com and get the following answer:
The two IP numbers 68.180.206.184 and 98.139.102.145 together
There are several thousand of host names that point to the two IP numbers 68.180.206.184 and 98.139.102.145 together, hereafter referred to as "IP group 1".