bad referral

[Barry Margolin]

In article <3.0.3.32.20000624162726.01D97C80 at POP3.HANK.ORG>,
Bill Moseley  <moseley at hank.org> wrote:
>I'm trying to learn by other peoples mistakes here.
>
>  bad referral (AMAZON.com !< www.amazon.com)
>
>I know this is a rather common question on this list, but I'm trying to
>figure out exactly what's wrong with amazon's setup to cause this -- and in
>the process gain a better understanding of bind.
>
>After spending a while looking at dig and nslookup queries I'm a bit confused.
>
>I'm not great at using the dig tool, but:
>
>dig www.amazon.com. ns @AUTH00.NS.UU.NET.
>
>;; ANSWER SECTION:
>www.amazon.com.         1D IN NS        ns-20.amazon.com.
>www.amazon.com.         1D IN NS        ns-10.amazon.com.
>
>Ok, it says look at ns-20.amazon.com.  But then:
>
>dig www.amazon.com. ns @ns-20.amazon.com.
>;; got answer:
>;; ns_initparse: Message too long
>
>I'm not sure what the answer is I'm getting.  What's "Message too long" mean?

It essentially means that the response isn't formatted properly.  I
snoop'ed a query and saw that even though it contains answers, the Answer
Count field in the header is 0.  There's more data in the packet than there
should be according to the header, so it's too long.

>Is it that they have delegated www.amazon.com to ns-20, yet ns-20 has no NS
>record for the zone?

It's probably a Cisco Distributed Director.  You can configure A and SOA
records on them, but they don't have NS records on them.

They've always had some problems implementing the DNS protocol fully.
However, the problems don't impact the queries they're designed to support,
so it's not usually a problem.  For instance, there's no reason for you to
ask it explicitly for NS records.  When you're trying to connect to
www.amazon.com, you should ask it for the A record.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Burlington, MA
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