----- Original Message -----
From: "Greg Hewgill" <greg(_at_)hewgill(_dot_)com>
To: <spf-discuss(_at_)v2(_dot_)listbox(_dot_)com>
Sent: Thursday, April 01, 2004 3:38 PM
Subject: Re: [spf-discuss] Just how many of the boxen really *need* to be in
the spf rr
On Thu, Apr 01, 2004 at 07:31:34PM +0200, Ernesto Baschny wrote:
reverse (just one possible):
This is a bit off topic, but I've seen multiple PTR records for one ip
address,
for example 64.251.192.200 has 245 different PTR records. I can't help but
think this is violating some established practice somewhere.
That's exactly the sort of whackiness I want to avoid. I've seen this done
in some weird ways, such as getting all SSH keys to do their reverse DNS and
come up with the same hostname with the same already-registered keys. (Yes,
this was an insane variant.) I'm extremely reluctant to add a "reasonable"
limitation that will break things in some border cases when it's really not
necessary.
And there are plenty of cases, such as dial-up modem pools and cable-modem
pools, where management of the forward and reverse DNS is quite disjoint and
may be unsynchronized for hours, depending on two different expiration
times. Add in the old Windows 24-hour timeout on cached DNS information that
drives web-hosting companies *insane* when relocating their services
dynamically, and asking for a matching reverse PTR quickly becomes
unreasonable.