We pick a.root-servers.net, one of the 13 root servers (1), and ask it about s102-blog.comunidades.net and learn that net is delegated to 13 name servers (2), so we ask k.gtld-servers.net where we learn that comunidades.net is delegated to two name servers, including dns2.comunidades.net (3), so we ask that one and get the following answer:
