Multiple A records and reverse DNS

[Thomas Schulz]

> > That is mostly how I thought it worked. What I had in mind more
> > specifically was:
> > 
> > adi.com zone:
> > mackerel.adi.com.  IN  A  75.100.245.141
> > mackerel.adi.com.  IN  A  96.85.104.76
> > 
> > reverse zones:
> > 141.245.100.75.in-addr.arpa.  IN  PTR  mackerel.adi.com
> > 76.104.85.96.in-addr.arpa.    (not yet set up)
> 
> OK, suppose you then set up 
> 
> 76.104.85.96.in-addr.arpa.     IN  PTR  mackerel.adi.com.
> 
> That may not play well with all the SMTP servers you wish to send to,
> due to subtle implementation variations. 
> 
> > But receiving mail on both was more work than I had expected, so I am
> > not going to set that up. 
> 
> Many sites have separate incoming and outbound SMTP servers. There is
> no reason to name them the same, especially not when you plan to
> implement them on separate IP addresses/ranges. 
> 
> The important thing is that the A and PTR records agree. That is most
> simply done by using a single A record for each name, and a single PTR
> record for each IP.

Thanks to everyone for all the information.
This was all to be temporary while switching from one ISP to another.
The new ISP has to set up the pointer records, hopefully delegating to
our server. They are taking a long time getting back to us on what they
can do. Fortunately we will still have service with our old ISP for
quite awhile. I just thought that receiving email from both addresses
would make the timing of the final switch over less critical.

Tom Schulz
Applied Dynamics Intl.
schulz at adi.com