go
ce.eq.edu.au has one IP number , which also has a corresponding reverse pointer. webmail.eq.edu.au point to the same IP. eq.edu.au is a domain controlled by two nameservers at eq.edu.au themselves. They are on the same IP network. Incoming mail for eq.edu.au is handled by two mailservers also at eq.edu.au. Two mailservers have the same IP number. eq.edu.au has one IP number. ce.eq.edu.au is hosted on a server in Australia.

ce.eq.edu.au
a records
 
+ 203.10.121.51 203.10.121.0/24 AS9650 -
+ --- -

eq.edu.au
a records
 
+ 203.10.121.50 203.10.121.0/24 AS9650  
+ ---  
ns-soa records
 
+   AS?  
+ ---  
ns records
ns1.eq.edu.au
+ 203.10.121.40 203.10.121.0/24 AS9650 -
+ --- -
ns2.eq.edu.au
+ 203.10.121.41 203.10.121.0/24 AS9650 -
mx records
mxa.eq.edu.au
+ 203.10.121.2 203.10.121.0/24 AS9650 mx.eq.edu.au
+ --- mx.eq.edu.au
mxb.eq.edu.au
+ 203.10.121.2 203.10.121.0/24 AS9650 mx.eq.edu.au
ip numbers of host
203.10.121.51
ptrs of ip numbers
ce.eq.edu.au
ip numbers using ptr to this host
203.10.121.51
hostnames sharing ip with a-records
webmail.eq.edu.au