no caching a forwaded aswers

Kevin Darcy kcd at
Mon Mar 26 19:07:53 UTC 2001

0 TTL is legal.

Perhaps you are beginning to realize the limitations of using DNS as a
load-balancing mechanism. You can only get it to operate semi-reliably by
*disabling* one of the most important features of the protocols (i.e.

This is why high-performance load-balancing is usually done at a lower
level than DNS, e.g. Cisco Local Director. The best you can get from
DNS alone is *rough* load-balancing, and only at the cost of increasing
DNS traffic significantly for your server and all of the servers that are
querying it.

- Kevin

Roger Caspar wrote:

> I have a dns Server bind 8.2.3 (Server1) with different Zone and one
> Zone is forward to another Name Server (Server 2)
> who manage this zone.
> The request from the Client looks like:
> Client request to Server 1
> <---------------------------------------------
> |
> |
>    Server 1 ---> forward to Server
> 2                                                         |
> |
> |
>                             answer from Server 2 to Server 1 --->
> answer from Server 1 to Client (and caching on Server 1)
> My problem is now that the Server 1 cache the request for the request
> where is frowarded to Server 2. He shouldn't cache this information,
> then this answer can be different from one request to another (Server
> load balancing).
> I tried it with a very low TTL for this Zone, but when I use 1 sec, it
> will cache for more then one minute.
> Can I set a TTL value "zero", and what mean that, it will not cache
> every information about this zone??
> Can every NameServer understand this value or what can it happen??
> I realy need a solution where every Name Server (on Solaris or NT  etc.)
> doesn't cache my information.
> I hope to get some feedback.
> Thanks in advance
> Best wishes
> Roger

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