We pick l.root-servers.net, one of the 13 root servers (1), and ask it about cc.kuleuven.be and learn that be is delegated to five name servers (2), so we ask m.ns.dns.be where we learn that kuleuven.be is delegated to three name servers, including dns2.kulnet.kuleuven.be (3), so we ask that one and get the following answer:
Cc.kuleuven.be is a domain controlled by two domain name servers at kuleuven.be having a total of four IP numbers. Some of them are on the same IP network. Incoming mail for cc.kuleuven.be is handled by six mail servers also at kuleuven.be having a total of six IP numbers. There are three duplicated IP numbers. All six of them are on the same IP network.