More Than One Zone on a Name Server Question

[Kevin Darcy]

Tom Naves wrote:

>In  1.168.192.in-addr.arpa I have a PTR Record:
>
>192.168.20.134	IN	PTR	mail.mydomain.com.
>
>and
>
>192.168.20.131	IN	PTR	mail2.mydomain.com.
>
Those entries do not belong in the 1.168.192.in-addr.arpa zone.

>Since mail.mydomain.net is also the alternate mail exchanger for 
>mydomain.com and mail.mydomain.com is the alternate mail exchanger for 
>mydomain.net how would I handle it?  Would this be good?
>
>192.168.20.134  IN      PTR     mail.mydomain.com.
>   		IN	PTR	mail2.mydomain.net.
>192.168.20.131	IN	PTR	mail2.mydomain.com.
>   		IN	PTR	mail.mydomain.net.
>
>or do I need to put a second ip addr on the interface on each server?
>
>or do I just forget about PTR records for these addresses?
>
Are you under the impression that MX records can only point to names in 
the same zone as their owners? Just pick one domain as your "primary" 
domain, give your mail servers names in that domain, and then point all 
of your MX records to those names. There's nothing wrong with pointing 
the MX records for mydomain.com to names in the mydomain.net zone. It's 
done all of the time. Our main inbound servers are in the 
extra.daimlerchrysler.com zone, for instance, and we have MX records in 
several other domains (e.g. dcx.com, cfc.com) pointing to those servers. 
If you have the same set of names for all of your MX targets, then 
reverse DNS for those targets stays clean and simple.

Having multiple PTRs owned by the same in-addr.arpa name, in contrast, 
is not only awkward and non-scalable, but AFAIK a waste of time since 
nothing looks beyond the first record in the response anyway.

- Kevin

>On Thu, 17 Feb 2005, Sebastian Castro Avila wrote:
>
>  
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>>It seems you are a little bit confused about your zones.
>>
>>In "mydomain.com" zone file, you declare records under that zone
>>"test.mydomain.com", "arthur.mydomain.com", etc.
>>
>>Within your reverse zones (probably 1.168.192.in-addr.arpa) you define
>>records under that zone (131.1.168.192.in-addr.arpa pointing to
>>"mail.mydomain.net", 144.1.168.192.in-addr.arpa pointing to
>>"linux.mydomain.com", etc).
>>
>>So, you must create records under the corresponding zone.
>>
>>I hope it helps
>>-- 
>>Sebastian E. Castro Avila             sebastian at nic.cl
>>Administrador de DNS, NIC Chile
>>Fono: (2) 9407705                  Fax  : (2) 9407701
>>
>>
>>
>>    
>>
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