On Tue, 29 Oct 2002 10:54:02 GMT, Sean Jones
<sean(_dot_)jones(_at_)micromedical(_dot_)co(_dot_)uk> said:
Why would MS (or anyone for that matter) want multiple pointer records when
one will suffice. My thoughts revolved around clustered servers, .net & etc In
short the Microsoft-verse.
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...
In reality it doesn't matter two hoots what MS do, they will still have to
inter-operate with the rest of the Internet per se, unless you believe the
scare mongering that with .Net MS want to make a corporate Internet which they
control.
Note that Microsoft is being very careful to fight the .Net war at the
application level and leave transport and lower alone, simply because they
know they need to interoperate.
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.
--
Valdis Kletnieks
Computer Systems Senior Engineer
Virginia Tech
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