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List:       djbdns
Subject:    Re: is this a serious problem
From:       Georgi Georgiev <chutz () gg3 ! net>
Date:       2004-01-31 23:34:55
Message-ID: 20040131233455.GB24651 () lion ! gg3 ! net
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maillog: 31/01/2004-10:17:03(-0600): mw-list-dns@csi.hu types
> On Fri, Jan 30, 2004 at 01:36:45PM -0500, Paul Jarc wrote:
> > mw-list-dns@csi.hu wrote:
> > > So how can I figure out, using djbdns tools, whether
> > > ns2.sztaki.hu really has the record or it answers from cache?
> > 
> > Try non-recursive queries with dnsq every so often.  If you ever find
> > that it doesn't know, but a recursive query afterwards gets the
> > answer, then it was answering from cache.  If you never find that it
> > lacks the answer with dnsq, then you never know.
> 
> Actually, there was a way to figure out that in fact ns2.sztaki.hu,
> one of the nameservers for hu, was answering from cache when queried
> for NS records for csi.hu.  Indeed, my dnsq query
> 
> dnsq ns csi.hu ns2.sztaki.hu
> 
> had (two) `answer:' lines in it.  But apparently now they fixed it,
> and I get
> 
> $ dnsq ns csi.hu ns2.sztaki.hu
> 2 csi.hu:
> 91 bytes, 1+0+2+2 records, response, weird ra, noerror
> query: 2 csi.hu
> authority: csi.hu 86400 NS a.ns.csi.hu
> authority: csi.hu 86400 NS b.ns.csi.hu
> additional: a.ns.csi.hu 180869 A 141.225.11.87
> additional: b.ns.csi.hu 180869 A 141.225.37.221

What is it that they fixed? Look at the TTL in the additional section. I guess
they do answer from cache after all.

$ for i in 1 2; do dnsq ns csi.hu ns2.sztaki.hu; sleep 5; done

2 csi.hu:
91 bytes, 1+0+2+2 records, response, weird ra, noerror
query: 2 csi.hu
authority: csi.hu 86400 NS b.ns.csi.hu
authority: csi.hu 86400 NS a.ns.csi.hu
additional: a.ns.csi.hu 254717 A 141.225.11.87
additional: b.ns.csi.hu 254717 A 141.225.37.221
2 csi.hu:
91 bytes, 1+0+2+2 records, response, weird ra, noerror
query: 2 csi.hu
authority: csi.hu 86400 NS b.ns.csi.hu
authority: csi.hu 86400 NS a.ns.csi.hu
additional: a.ns.csi.hu 254712 A 141.225.11.87
additional: b.ns.csi.hu 254712 A 141.225.37.221

-- 
\    Georgi Georgiev   \  Now there's three things you can do in a     \
/     chutz@gg3.net    /  baseball game: you can win or you can lose   /
\   +81(90)6266-1163   \  or it can rain. -- Casey Stengel             \
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