Maintained by: NLnet Labs

[Unbound-users] negative cachetime

A. Schulze
Tue Mar 10 08:04:31 CET 2015


Hello,

we run in an issue with cached negative answers and need clarification.

at t=0 a client ask unbound for test.example.org.
unbound does not know anything about the domain and ask the nameserver  
ns1.example.org.
the answer is NXDOMAIN.

at t=1, some seconds later, the nameserver is reconfigured and now  
test.example.org exist.

at t=3 the same or an other client ask unbound again for test.example.org.
the answer is still NXDOMAIN. t=3 is more then 14 hours later.

How long I have to wait until unbound forget the NXDOMAIN
and fetch new data from authoritative server? Could that be controlled  
somehow?

The SOA-Reord for example.org looks like this:
example.org. 12967 IN SOA example.org. hostmaster.example.org.  
1501261358 43200 7200 2419200 86400

There was a similar question a year ago about min and max negative ttl  
without results.
http://unbound.net/pipermail/unbound-users/2014-February/003194.html

Andreas