We pick l.root-servers.net, one of the 13 root servers (1), and ask it about sohu.com and learn that com is delegated to 13 name servers (2), so we ask m.gtld-servers.net where we learn that sohu.com is delegated to four name servers, including dns.sohu.com (3), so we ask that one and get the following answer:
sohu.com is a domain owned by Sohu Internet, a Chinese Internet company. Located in Beijing, the company was selected in 2005 to create and maintain the official Beijing Olympics 2008 website. Sohu.com is a domain controlled by four domain name servers at sohu.com themselves. All four of them are on different IP networks. Incoming mail for sohu.com is handled by three mail servers also at sohu.com having a total of three IP numbers. Two mail servers have the same IP number. All three of them are on different IP networks. Sohu.com has two IP numbers (18.104.22.168, 22.214.171.124). Both are on the same IP network.
All of them use the four name servers dns, ns1, ns2 and ns4.sohu.com together, hereafter referred to as "name server group 1".
The four name servers dns, ns1, ns2 and ns4.sohu.com together
All of the three domains that use name server group 1 point to the two IP numbers 126.96.36.199 and 188.8.131.52 together, hereafter referred to as "IP group 1". Worth noting is that three of the host names that point to IP group 1 use name server group 1.
The name server dns.sohu.com
There are about twenty domains that use the name server dns.sohu.com.