[dns-operations] Odd EDNS implementation bug

Mark Andrews marka at isc.org
Thu May 27 00:14:41 UTC 2010

In message <20100526232957.5B0C25406E at smtp.geoff.co.uk>, "Geoffrey Sisson" writ
> marka at isc.org (Mark Andrews) wrote:
> > In message <alpine.LSU.2.00.1005261924540.28459 at hermes-2.csi.cam.ac.uk>, To
> ny Finch writes:
> > > Some rr.com name servers put the answer RRset in the additional ssection
> > > if you make an EDNS request:
> > I suspect that it is a specialized server synthesizing responses
> > on the fly and it hasn't been properly tested.  You can't just
> > append answers to queries and have it work.
> Looking at this on the wire, it seems the OPT RR is in the answer section
> and the answer is in the additional section, so it looks like they just
> have the RRs in the wrong order.
> Geoff

Which is what you get when you append the answer to the query. :-)

If you play around with the edns buffer size you will see it change
in the response to match that of the query.  This type of bug has
been seen before.  If they were just putting the records in the
order then the buffer size would not change.

Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org

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