why does dig +trace change outcome?

Hal Brooks hal at uga.edu
Sat Jun 21 23:14:02 UTC 2008

On Sat, 21 Jun 2008, Genco Yilmaz wrote:

> On Sat, Jun 21, 2008 at 5:53 PM, Hal Brooks <hal at uga.edu> wrote:
>> Some name servers, but not all, are unable to resolve
>> krensavage.com
>> But even those which are ordinarily unable to resolve
>> krensavage.com seem to be able to get answers with dig if
>> the +trace option is used.
>> For example, this web site:
>> http://www.kloth.net/services/dig.php
>> offers a browser interface to dig.  If you use their
>> localhost as the server and query for an A record, but
>> don't specify "trace", then the unhappy result is
>> "connection timed out; no servers could be reached", but if
>> you do specify "trace" then you get 6 answers.
>> Similarly from the command line:
>>        dig @dns1.uga.edu krensavage.com        # times out
>>        dig @dns1.uga.edu krensavage.com +trace # OK
>> But other name servers handle it fine (and dig works
>> even without +trace):
>>        dig @ns1.usg.edu krensavage.com         # OK
>>         dig @ns1.usg.edu krensavage.com         # also OK
>> The only shortcoming I see with the krensavage.com setup is
>> that the whois record only has 1 name server
>> (yns1.yahoo.com) listed.
>> For comparison, olivebarn.com, has similar characteristics
>> (though the whois record lists both yns1.yahoo.com and
>> yns2.yahoo.com), but it doesn't result in the same failures
>> I'm seeing for krensavage.com.
>> Any and all help appreciated.
>> -hal
> Hello Hal,
>    This domain has been delegated to only 1 NS server at root servers.
> #dig +short +norec ns krensavage.com @a.gtld-servers.net
>  yns1.yahoo.com.
> Whereas, authoritative server lists 3 other servers;
> #dig +short +norec ns krensavage.com @yns1.yahoo.com
> ns8.san.yahoo.com.
> yns2.yahoo.com.
> yns1.yahoo.com.
> ns9.san.yahoo.com.
> I suppose, it is better to fix this mismatch first.  Because trace option
> causes dig to make iterative queries,
> you don't see the response from the cache.

Thanks, I'll try to get the RP to do that.  But 
krensavage.com isn't my domain.  I'm just trying to get the 
uga.edu NS to be able to see it.  And since some others can 
get it, it's difficult for me to say that the problem is 
with their config and not mine.


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