go
ca03.cira.ca has one IP number , but the reverse is b.ca-servers.ca. b.ca-servers.ca point to the same IP. cira.ca is a domain controlled by two nameservers at cira.ca themselves. They are on the same IP network. Incoming mail for cira.ca is handled by four mailservers. Two of them are on the same IP network. cira.ca has one IP number. ca03.cira.ca is hosted on a server in Canada.

ca03.cira.ca
a records
 
+ 192.228.25.45 192.228.25.0/24 AS27299 b.ca-servers.ca
+ --- b.ca-servers.ca

cira.ca
a records
 
+ 192.228.29.1 192.228.29.0/24 AS27299  
+ ---  
ns-soa records
ns01.cira.ca
+ 192.228.26.135 192.228.26.0/24 AS27299 mail01.tor.cira.ca
+ --- mail01.tor.cira.ca
ns records
ns01.cira.ca
+ 192.228.26.135 192.228.26.0/24 AS27299 mail01.tor.cira.ca
+ --- mail01.tor.cira.ca
ns02.cira.ca
+ 192.228.26.136 192.228.26.0/24 AS27299 mail02.tor.cira.ca
+ --- mail02.tor.cira.ca
mx records
office-mx.cira.ca.cira.ca
+   AS?  
+ ---  
mail.cira.ca
+ 192.228.29.17 192.228.29.0/24 AS27299 -
+ --- -
mail01.tor.cira.ca
+ 192.228.26.135 192.228.26.0/24 AS27299 -
mail02.tor.cira.ca
+ 192.228.26.136 192.228.26.0/24 AS27299 -
ip numbers of host
192.228.25.45
ptrs of ip numbers
b.ca-servers.ca
hostnames sharing ip with a-records
b.ca-servers.ca
domains using this as nameserver under another name
ca
ca-servers.ca