[Blink] outbound proxy not used
Dan Pascu
dan at ag-projects.com
Thu Sep 30 16:40:32 CEST 2010
On 30 Sep 2010, at 13:13, Mr. Cookie wrote:
> Just an idea. How about to run some test DNS query via normal OS
> resolving (supposed to be answered with known SRV/NAPTR containing
> response). On failure switch to built in resolver assuming there is
> broken router resolving on the way.
And how do you distinguish a failure in the local resolver vs a
failure in that particular DNS you query (network failure, server
failure, ...)?
Besides asking the authoritative nameserver is always correct, as that
nameserver should be the most appropriate source that knows the
answer. Any local resolver should only be used for caching purposes
and querying them should not return something else. The main problem
is that local resolvers are often broken when it comes to NAPTR and
SRV records and they do not return what the authoritative nameserver
knows they return NXDOMAIN as if the record doesn't exist, making it
impossible to figure out if there is indeed no record or the local
resolver is just broken. Thus always asking the authoritative
nameservers is the simplest solution to avoid broken resolvers.
--
Dan
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