[dnsdist] Many "NS ." requests

[Winfried]

On 26.08.25 14:57, Stephane Bortzmeyer wrote:
> On Tue, Aug 26, 2025 at 02:52:21PM +0200,
>   Winfried via dnsdist <dnsdist at mailman.powerdns.com> wrote
>   a message of 25 lines which said:
>
>>>> topQueries(30)
>>>      1  .                                        7906 39.5%
>>>
>>> Which is probably not normal.
>>>
>> "." is not on the topQueries() list on a very busy dnsdist (Resolver
>> loadbalancer) here. Is it possibly a (dnsdist) health-check?
> Probably not since it is sent to the backend (I can see it by snooping
> the link between dnsdist and the backend). Which is strange since, at
> least, dnsdist should serve it from its cache.
>
We see many queries for google.com containing opcode 2 (status), which 
are dropped by Recursor. Maybe the ". NS" queries you see has also a 
wrong opcode or something else and are dropped by the backend as well?