Multiple PTR records
Chris Buxton
cbuxton at menandmice.com
Thu Jan 15 18:19:00 UTC 2009
On Jan 15, 2009, at 6:33 AM, Halassy Zoltán wrote:
> My configuration:
>
> Have a router, two computers behind it. comp1 has webserver (no
> mailserver), comp2 has mailserver (no webserver), have one IPv4
> address, and few IPv6 addresses. The IPv4 address configured on the
> router, DNAT-ing the TCPv4 ports to one of the computers (80 ->
> comp1, 25 -> comp2, etc). IPv6 is natively routed.
>
> I don't want to break forward <-> reverse mapping.
>
> So the config would be something like this:
>
> example.com. MX 10 mail.example.com.
> www.example.com. A 1.2.3.4
> mail.example.com. A 1.2.3.4
> www.example.com. AAAA 2001::1234:1
> mail.example.com. AAAA 2001::1234:2
> 1.0.0.0.4.3.2.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.2
> .ip6.arpa. PTR www.example.com.
> 2.0.0.0.4.3.2.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.2
> .ip6.arpa. PTR mail.example.com.
> 4.3.2.1.in-addr.arpa. PTR www.example.com.
> 4.3.2.1.in-addr.arpa. PTR mail.example.com.
>
> Would this one break anything? Or anyone else have a better tip how
> could i handle this situation? Multiple PTRs in this case is really
> an issue?
Yes, it is an issue. Remove this record:
4.3.2.1.in-addr.arpa. PTR www.example.com.
Your web server doesn't need a PTR record.
> The main thing i don't want to break forward <-> reverse symmetry
> cause there are some sanity checks about this (like in spamfiltering).
Right, your mail server ought to have a PTR record. Your web server,
however, does not need it.
Chris Buxton
Professional Services
Men & Mice
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