Good Morning Valdis
-----Original Message-----
From: Valdis(_dot_)Kletnieks(_at_)vt(_dot_)edu
[mailto:Valdis(_dot_)Kletnieks(_at_)vt(_dot_)edu]
Sent: 29 October 2002 15:39
To: Sean Jones
Cc: ietf(_at_)ietf(_dot_)org
Subject: Re: Palladium (TCP/MS)
You're close. You'd want this for multihomed servers, so a
PTR query works
as you'd expect. Consider this case:
www.big-corp.com A 10.0.0.10
A 192.186.10.10
mail.big-corp.com A 10.0.0.10
A 172.16.23.10
Then you'd want to have PTRs as follows:
192.168.10.10 PTR www.big-corp.com
172.16.23.10 PTR mail.big-corp.com
(and then the magic)
10.0.0.10 PTR www.big-corp.com
PTR mail.big-corp.com
If you don't have 2 PTR records for that last, you can get
into the situation where a system will look up the A record for www, get the
IP
address, then do a PTR to sanity-check, get back only the mail. address,
and get upset. Having both PTR records means that you'll be able to find one
to match to the original hostname either way...
Forgive my ignorance, but I thought email was handled by Mail eXchange (MX)
records, thus a PTR would not be required?
Thinking along a bit more, setting the routers shouldn't be
a big issue, after all Cisco have been producing routers IPv6 capable
for a fair while now, so surely they could incorporate multiple PTR records
within the routers capability?
Routers don't have anything at all to do with PTR records.
What I said was that if a company wanted to block all access to
Microsoft's servers, they'd have to keep continual track of all the IP
addresses
in use - which can be interesting if round-robin DNS or other similar things
are in use.
I understand where I went wrong. But I doubt that any commercial enterprise
would want to block access to MS servers in RL.
Regards
Sean Jones