Ptr records question

[oliverdaniel]

hello,

i would like to know if anyone could help me with the following:

when i create a ptr under an owned ip, the ptr and everything resolves. and shows that the ptr is working.

yet my question is, how do i do for all the domains that are under one shared ip?

1) do i have to add a single ptr for all of them?
or
2) do i have to add a ptr for each one of them? does it even matter if they dont have the same ptr, but are all under the same ip?

i would truly appreciate it if someone could help me with this.

thank you,
oliver.

 

[ranz]

In answer to your question: you could do both.

However, if it were me, and you'd want to save on workload, I would do it for a single ptr record. Then, if a client requests, on an individual basis, add them in.

 

[floyd]

My understanding is that you can (should) only have one ptr record for each ip.

 

[nobaloney]

Floyd is correct. There's no definition in RFCs for how to handle multiple rDNS entries for an IP#, so using them could cause problems. Most certainly what will NOT happen is you'll get the rDNS entry you want, as if there's more than one PTR record DNS will return all of them, in random order.

o if for example you have example.com, example.net, and example.org, all pointing to the same IP#, and you do:

dig example.com

and ret a response of 192.168.3.3, and then do:

dig -x 192.168.3.3

you might very well get example.org.

Jeff