We pick d.root-servers.net, one of the 13 root servers (1), and ask it about vip-bxkpoa.terra.com.br and learn that br is delegated to six name servers (2), so we ask d.dns.br where we learn that terra.com.br is delegated to four name servers, including c.dns.terra.com (3), so we ask that one and get the following answer: