We pick d.root-servers.net, one of the 13 root servers (1), and ask it about www.hr and learn that hr is delegated to five name servers (2), so we ask ns.uu.net where we learn that www.hr is delegated to two name servers, including dns.tel.fer.hr (3), so we ask that one and get the following answer:
Www.hr is a domain controlled by two domain name servers at fer.hr. Both are on the same IP network. Incoming mail for www.hr is handled by one mail server at www.hr themselves. Www.hr has one IP number (126.96.36.199), which also has a corresponding reverse pointer.