Ascend Archive
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Re: (ASCEND) DNS resolution bug
So what is Ascend going to do about this. I'm getting IRC users that can't
get to certain servers because of this.
-Jesse Martinez-
CEO
East County Internet Services, Inc.
Voice (925)706-4280
Fax (925)706-4282
On Mon, 11 May 1998, Kevin A. Smith wrote:
> At 09:27 AM 5/8/98 -0700, Kit Knox wrote:
> >
> >There appears to be a problem with Ascend's DNS resolution code and hosts
> >with many A records. Could people with a minute to spare please do the
> >following :
> >
> >1. Telnet to any Ascend router.
> >2. Enter term serv mode.
> >3. Attempt to ping/traceroute to www.microsoft.com.
> >4. Record if the DNS lookup fails.
> >5. Let me know which nameserver you are using and what version of Bind it
> >is running.
>
> The problem is an old one that has just surfaced on our products. It's
> been around as Kit observes on other (including UNIX) platforms for a
> while. It relates to a section of the relevant RFC - where DNS replies
> of over 512 bytes is addressed.
>
> Conclusion so far...
>
> DNS is normally a UDP based protocol, however if the reply is longer than
> 512 bytes, the RFC recommends establishing a TCP connection. This is not a
> widely implemented portion of the RFC, as few DNS lookups require more than
> 512 byte responses.
>
> We have considered processing what we could (the first 512 bytes) and
> ignoring the TC bit. But that could have unpredictable consequences.
> The alternative is also unpredictable, since virtually no one else supports
> the TCP option, even if we did, it most likely wouldn't work.
>
>
> Kevin
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>
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