EDNS and Server 2003

[Mike Garner]

I've seen a few posts with regard to MS using a new RFC
and that some folks have had to disable EDNS on their
Server 2003 DNS boxes. I'm wondering if this is my
problem AND can someone point me to an article with more
information.

My symptoms are as follows. Both of my DNS boxes (one
primary one secondary) are Server 2003. They were running
Win2k. When running Win2K, all was well. After the
upgrade to Server 2003 some clients are having problems
resolving the IP addresses for random, seemingly
unrelated internet hosts, mail.yahoo.com is one such
host. I know these sites are up and the problem is with
my DNS. Its as if sometimes the DNS servers are
forwarding the requests on the higher level DNS servers.
Its strange. If I use some of my other (off-site, higher
level) DNS Servers in my clients, the sites resolve
fine. What's the deal with these Server 2003 DNS boxes?
Is this the EDNS problem?

Thanks in advance.
Mike

[Jonathan de Boyne Pollard]

MG> [...] can someone point me to an article with more information.

How about the Microsoft DNS server documentation itself ?

<URL:http://www.microsoft.com./technet/prodtechnol/windowsserver2003/proddocs/entserver/sag_DNS_imp_EDNSsupport.asp?frame=true>

MG> mail.yahoo.com is one such host.

EDNS0 will indeed cause a larger datagram size to be negotiated
during query resolution for that domain name, in order to hold
all of the "glue".

Ironically, this is a good example of a case where the use of EDNS0
is a complete waste of effort. The "glue" involved forms part of a
referral that is outside of the "yahoo.com." content DNS servers'
bailiwick (because it is for "net."). Secure resolving proxy DNS
servers will discard it completely, for being potential cache poison.
All that the use of EDNS0 does is increase the number of data that
are transferred only to then be discarded unused.