Maintained by: NLnet Labs

[Unbound-users] Setting TTLs via scriptable interface does not change cached ttls

Jay Deiman
Wed Jan 16 00:52:47 CET 2013


On 01/15/2013 12:18 AM, W.C.A. Wijngaards wrote:
> Hi Jay,
> 
> On 01/14/2013 09:31 PM, Jay Deiman wrote:
>> I've written some code based on the ttl modification code here:
> 
>> http://www.unbound.net/documentation/pythonmod/examples/example3.html
> 
>>  I'm noticing an odd behavior that seems like it may be a bug.  I
>> was doing some testing and found that my responses that I get back
>> from unbound for the modified TTLs seem to be correct, but the
>> cached entries don't expire when the TTL reaches zero.
> 
> 
> The cache entry itself, the message, has its own TTL (usually the
> minimum of the TTLs of the RRs but you broke that assumption with your
> code), you are adjusting the TTL of the RRs, but not the TTL of the
> message.  This is causing your strange observations.

So, is the only way to modify the TTL of the stored message to
instantiate a new DNSMessage and use that as my response, which has a
massive performance penalty, or is there another way?

Thanks,

Jay