We pick k.root-servers.net, one of the 13 root servers (1), and ask it about inwx.cn and learn that cn is delegated to six name servers (2), so we ask b.dns.cn where we learn that inwx.cn is delegated to two name servers, including dns7.hichina.com (3), so we ask that one and get the following answer:
Inwx.cn is a domain controlled by two domain name servers at hichina.com having a total of twelve IP numbers. Some of them are on the same IP network. Incoming mail for inwx.cn is handled by one mail server at qq.com. We are missing the IP:s of one server: mxdomain.qq.com.