Fwd: Re: Fwd: Re: Difference between netstat & rndc status

Cathy Almond cathya at isc.org
Tue Jul 5 07:26:58 UTC 2011

On 05/07/11 06:25, Bind wrote:
> -----Original Message-----
>  From: "Bind" <bind at dci.ir>
>  To: "Mark Andrews" <marka at isc.org>
>  Date: Tue, 05 Jul 2011 09:55:03 +0430
>  Subject: Re: Fwd: Re: Difference between netstat & rndc status
> Thanks for your best support and answers all the time.
> Could u explain more about this list. how it built and when it refreshed?
> Regards

When a client makes a query of a recursive server, sometimes the answer
can be given immediately from cache (or from authoritative data if the
server is both authoritative and recursive).  However, if the server
needs to perform iterative resolution of the query on behalf of the
client by sending it's own queries to authoritative servers
elsewhere,then it has to keep a record of the original client query
while this is happening so that it can respond when the answer is

If the same client makes multiple queries for different names, then
these are all recorded separately since each is due its own answer.

When the server responds to the client, then the entry is removed from
the list.

If a client doesn't see the server response, it doesn't mean that the
entry isn't removed from the list, it means that the server responded
after the client timed out (this sometimes happens if there are problems
resolving the query).

Duplicate client queries are identified (for example if the client
retries) and stored as a single 'recursive client'.

If the list reaches the 'soft' limit (this is the number in the middle)
then named starts timing out (SERVFAIL) the longest waiting client
queries earlier than it would normally in order to make room for new

If the list reaches the 'hard' limit, then there is nowhere to put new
queries and named will not be able to process them.

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