serve-expired: "yes" and cache-min-ttl: 30 unsafe?
nicku at nicku.org
Thu Nov 15 19:26:16 UTC 2018
On 15/11/18 11:13 +0100, Ralph Dolmans via Unbound-users wrote:
>Sorry to hear Unbound has caused you problems. I'm trying to figure out
>the reason of the observed SERVFAIL responses.
>Was the serve-expired and cache-min-ttl configured on the Unbound
>instance that has the forward configured, or the instance the queries
>are forwarded to? Or both?
>Any change the SERVFAILS were only for DNSSEC signed domains?
No, a particular name in our domain which is not signed often came
back with SERVFAIL after it expired from the cache.
>Did you had a change to see the reason for the SERVFAIL responses in
>the Unbound log? Maybe the forwarder was returning expired DNSSEC
There were many SERVFAIL responses for queries for DS records.
>On 25-10-18 09:10, Nick Urbanik via Unbound-users wrote:
>> Dear Folks,
>> Thank you for an excellent piece of software.
>> I am puzzled by the behaviour of our multi-level DNS system which
>> answered many queries for names having shorter TTLs with SERVFAIL.
>> By multilevel, I mean clients talk to one server, which forwards to
>> another, and for some clients, there is a third level of caching.
>> So it was unwise to add:
>> serve-expired: "yes"
>> cache-min-ttl: 30
>> to the server section of these DNS servers running unbound 1.6.8 on
>> up to date RHEL 7? Please could anyone cast some light on why this
>> was so? I will be spending some time examining the cause.
>> If you need more information, please let me know.
Nick Urbanik http://nicku.org nicku at nicku.org
GPG: 7FFA CDC7 5A77 0558 DC7A 790A 16DF EC5B BB9D 2C24 ID: BB9D2C24
More information about the Unbound-users