Very Strange Reverse DNS problems

[Kirk Bradel]

Gary Galloway wrote:
> The response seem to be different depending on who does the lookup. For example our upstream provider AT&T who deligated the addresses to us gets good responses. However dnsstuff.com and roadrunner.com fail to do proper reverse lookups.  One of the address is 12.109.202.11  which is my mail server.  You can look at this using ns2.budgetphone.com as it is one of the DNS servers that does not respond properly.  It however responds correctly when you look at 12.109.202.9,  12.109.202.89, and 12.109.202.251 as well as many other addresses in the range. Below is what happens at dnsstuff.com  As you can see ns2 refers the request for .11 back to AT&T in this case but will often send it back to the root server as well. However it responds properly to the request for .251 which is in the same zone. Also below is a copy of an nslook session with ns2 from outside my local network showing proper responses for the lookup of 12.109.202.11  I suspect a cname or ptr problem at AT&T but h
ave
>   not been able to prove it.
> 
> How I am searching:
> Asking b.root-servers.net for 11.202.109.12.in-addr.arpa PTR record:  
>        b.root-servers.net says to go to dmtu.mt.ns.els-gms.att.net. (zone: 12.in-addr.arpa.)
> Asking dmtu.mt.ns.els-gms.att.net. for 11.202.109.12.in-addr.arpa PTR record:  
>        dmtu.mt.ns.els-gms.att.net [12.127.16.70] says to go to ns2.budgetphone.com. (zone: 202.109.12.in-addr.arpa.)
> Asking ns2.budgetphone.com. for 11.202.109.12.in-addr.arpa PTR record:  
>        ns2.budgetphone.com [12.109.202.3] says to go to cbru.br.ns.els-gms.att.net. (zone: 12.in-addr.arpa.)
> Asking cbru.br.ns.els-gms.att.net. for 11.202.109.12.in-addr.arpa PTR record:  
>        cbru.br.ns.els-gms.att.net [199.191.128.105] says to go to ns1.budgetphone.com. (zone: 202.109.12.in-addr.arpa.)
> Asking ns1.budgetphone.com. for 11.202.109.12.in-addr.arpa PTR record:  Reports mail.budgetphone.com. [from 12.109.202.2]
> 
> Answer:
> 12.109.202.11 PTR record: mail.budgetphone.com. [TTL 3600s] [A=12.109.202.11]
> 

Looks like  "ns2.budgetphone.com" does not have an answer for this PTR.


> 
> How I am searching:
> Asking c.root-servers.net for 251.202.109.12.in-addr.arpa PTR record:  
>        c.root-servers.net says to go to dmtu.mt.ns.els-gms.att.net. (zone: 12.in-addr.arpa.)
> Asking dmtu.mt.ns.els-gms.att.net. for 251.202.109.12.in-addr.arpa PTR record:  
>        dmtu.mt.ns.els-gms.att.net [12.127.16.70] says to go to ns2.budgetphone.com. (zone: 202.109.12.in-addr.arpa.)
> Asking ns2.budgetphone.com. for 251.202.109.12.in-addr.arpa PTR record:  Reports host251.budgetphone.com. [from 12.109.202.3]
> 
> Answer:
> 12.109.202.251 PTR record: host251.budgetphone.com. [TTL 3600s] [A=12.109.202.251]
> 
> 
>