Different answer when querying @server from different clients

Cathy Almond cathya at isc.org
Mon Mar 9 08:24:21 UTC 2015


On 08/03/2015 16:00, Steven Carr wrote:
> On 8 March 2015 at 13:50, Barry S. Finkel <bsfinkel at att.net> wrote:
>> Using "+trace" with "@8.8.8.8" ignores the "@8.8.8.8", as
>> that server is never queried when the query starts at the root
>> and moves down the DNS tree to authorized servers.
> 
> Incorrect, specifying @8.8.8.8 means that dig +trace will use 8.8.8.8
> to find the root servers and then continue to query the authoritative
> nameservers directly for any subsequent queries.
> 
> Steve

What happens with dig +trace is subtle, and not always what you want.

https://kb.isc.org/article/AA-00208

It's a limitation of the dig tool not being a fully-featured recursive
server with a temporary working cache (for intermediate results).

Far better to run your own iterative a non-recursive digs if you really
want to see what's happening.

Cathy



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