We pick a.root-servers.net, one of the 13 root servers (1), and ask it about c0.aero.afilias-nst.info and learn that info is delegated to six name servers (2), so we ask b2.info.afilias-nst.org where we learn that afilias-nst.info is delegated to four name servers, including ns1.yyz1.afilias-nst.info (3), so we ask that one and learn that aero.afilias-nst.info is delegated to four name servers (4), so we ask d0.aero.afilias-nst.org and get the following answer: