We pick h.root-servers.net, one of the 13 root servers (1), and ask it about dns.ao and learn that ao is delegated to six name servers (2), so we ask ns-ext.isc.org where we learn that dns.ao is delegated to four name servers, including ns02.dns.ao (3), so we ask that one and get the following answer:
Dns.ao is a domain controlled by four domain name servers at dns.ao and fccn.pt having a total of seven IP numbers. Some of them are on the same IP network. Incoming mail for dns.ao is handled by two mail servers at fccn.pt having a total of four IP numbers. Some of them are on the same IP network. Dns.ao has two IP numbers (2001:690:a00:1036:804::111, 220.127.116.11). Both are on different IP networks.
The two IP numbers 2001:690:a00:1036:804::111 and 18.104.22.168 together
Seven of the about twenty host names that point to IP group 1 use the three name servers ns01, ns02 and ns03.fccn.pt together, hereafter referred to as "name server group 2". Worth noting is that seven of the domains that use name server group 2 point to IP group 1.