Summary
vdc-hn01.vnn.vn has one IP number , which also has a corresponding reverse pointer.
0.162.203.in-addr.arpa point to the same IP.
abc.vn,
hmc.vn,
vnn.vn,
vnsc.vn,
s.vnn.vn and at least 100 other hosts use this as a nameserver.
vnn.vn is a domain controlled by two nameservers at
vnn.vn themselves. They are on different IP networks. Incoming mail for
vnn.vn is handled by two mailservers having a total of 14 IP numbers. Some of them are on the same IP network.
vdc-hn01.vnn.vn is hosted on a server in Vietnam.