Subject: RE: DNS query over anycast

From: "SESVOLD, DALE" <[email-masked]>
Date: Mon, 4 Jun 2001 07:46:21 -0500

Please excuse my ignorance, but I need some clarification.  Isn't the
anycast address for DNS used in a similar method to the neighbor discovery
with the link local multicast?  Shouldn't the host request the address of a
DNS server through the anycast address, and then when the unicast address is
presented back to the host it would initiate all DNS communication directly
on the proper unicast address?

| DALE G SESVOLD
| Senior Network Engineer
| MacAulay-Brown, Inc.
| Joint Information Operations Center
| J61, Information Operations Technical Analysis

-----Original Message-----
From: Steve Deering [mailto:[email-masked]]
Sent: Monday, June 04, 2001 1:25 AM
To: Randy Bush
Cc: [email-masked]
Subject: Re: DNS query over anycast

At 8:18 PM -0700 6/3/01, Randy Bush wrote:
>we poor stupid operators have to do something to overcome the mis-designs
>of the oh so brilliant but reality-challenged.
>
>while one can not measure all dns transactions, a significant number of
>them use just such a 'misconfiguration'.  please excuse our stupidity in
>wishing to continue to offer our customers better service.

Sigh.

This is the classic tradeoff between the expedient hack and an
alternative that accomplishes the same goal in a way that actually
fits with the way the system was designed to work, but takes some
more work to deploy.

If there is an urgent customer need to deploy IPv6 anycast DNS
transactions before the IPv6-capable DNS servers can be upgraded to
provide a unicast source address in response to an anycast query,
go ahead and (mis-)configure the servers to think an anycast address
is a unicast address.  Sure, this will work fine almost all of the time
(or else you wouldn't be advocating it).  ...

Steve

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From: Randy Bush <[email-masked]>
Date: Mon, 04 Jun 2001 06:48:47 -0700

> with the link local multicast?

nope.  most large isps have deployed dns caches on anycast, each isp a
different address, and tell their customers to point to that address.
it's just plain old dns, the request goes out, the reponse comes back.

randy