We pick m.root-servers.net, one of the 13 root servers (1), and ask it about arpa.manitu.net and learn that net is delegated to 13 name servers (2), so we ask g.gtld-servers.net where we learn that manitu.net is delegated to five name servers, including ns.umwelt-campus.de (3), so we ask that one and get the following answer:
Arpa.manitu.net is a domain controlled by two domain name servers at manitu.net having a total of four IP numbers. Some of them are on the same IP network.
Most of the more than a thousands domains that use the name server dns02.manitu.net use the two name servers dns01 and dns02.manitu.net together, hereafter referred to as "name server group 1", (example: baboo.at, jpu.at and kels.biz ).
The two name servers dns01 and dns02.manitu.net together
There are more than a thousands domains that use name server group 1.