[TriLUG] Re: AOL up to it's old tricks

[Jeremy Portzer]

On Tue, 2003-10-21 at 11:37, Dan Monjar wrote:

> I hit send too quickly... more to the point, how do you dynamic IP folks 
> handle the problem?  dyndns.org can supply a forward pointer for your IP 
> address (say monjar.dyndns.org pointing to 1.1.1.1) but since they don't 
> own the 1.1.1.0 block they can't setup the reverse record, right?

Most dynamic IP addresses have proper PTR records configured by the
ISP.  For example:

$ host portzer.com
portzer.com has address 24.136.134.178
$ host 24.136.134.178
178.134.136.24.in-addr.arpa domain name pointer
user-0c8h1li.cable.mindspring.com.
$ host user-0c8h1li.cable.mindspring.com.
user-0c8h1li.cable.mindspring.com has address 24.136.134.178

Since the forward address and reverse address are fine, 
24.136.134.178 <=> user-0c8h1li.cable.mindspring.com, then there is no
problem.  The fact that "portzer.com", my vanity name, points to that
same IP isn't really related -- as long as reverse DNS works, and the
record returned by reverse DNS works in the forward direction, then
everything's kosher.

Now, I suppose a truly restrictive spam protection system could require
that the delivery address's MX record match the name of the reverse
lookup, but that would block delivery to millions of addresses using
name-based virtual hosting.  I don't think you'll see this happen any
time soon.

--Jeremy
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