We pick b.root-servers.net, one of the 13 root servers (1), and ask it about sha.tc and learn that tc is delegated to five name servers (2), so we ask asia.zone.tc where we learn that sha.tc is delegated to two name servers, including ns1.footballmanager.ws (3), so we ask that one and get the following answer:
The two name servers ns1 and ns2.footballmanager.ws together
There are four domains that use name server group 1.
All of those use the primary name server ns1.footballmanager.ws. Worth noting is that all of the domains that use the primary name server ns1.footballmanager.ws use name server group 1.
All of them point only to the IP number 198.1.121.147.
All of them use only the IPv4 number 198.1.121.147. Worth noting is that all of the domains that only use the IPv4 number 198.1.121.147 use name server group 1.