[Unbound-users] negative cachetime

[A. Schulze]

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

[Patrik Lundin]

Post by A. Schulze
at t=3 the same or an other client ask unbound again for

test.example.org.

Post by A. Schulze
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?

Post by A. Schulze
example.org. 12967 IN SOA example.org. hostmaster.example.org.

1501261358 43200 7200 2419200 86400

The SOA minimum TTL is set to 86400 (24 hours). This is the value that

controls how long a NXDOMAIN is cached.

You can see the current remaining TTL by querying your cache with dig.

Forgot to include the list in my response.

Regards,
Patrik Lundin

[Dave Warren]

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