Stale cache feature problems
Borja Marcos
borjam at sarenet.es
Thu Nov 11 09:54:50 UTC 2021
> On 11 Nov 2021, at 10:40, Blažej Krajňák <blazej.krajnak at gmail.com> wrote:
>
> Hi,
>
> št 11. 11. 2021 o 10:28 Borja Marcos <borjam at sarenet.es> napísal(a):
>> First problem: I experienced random SERVFAILS with no apparent reason while i had the feature turned on. I think it
>> especially affected CDNs with multiple chained CNAMES and complex DNS server infrastructures.
>>
>
> glad to hear the confirmation of this problem. I experienced the same
> behaviour in our ISP network. Issue #2982
> https://gitlab.isc.org/isc-projects/bind9/-/issues/2982
>
> Please, add your conditions and findings to ticket.
I will.
I’ll add what I have for now, but it’s just anecdotal evidence.
I can try to get more debugging information including packet captures. I imagine it has something
to do with an interaction between CDNs (short TTL A records for DNS servers) and making the
wrong decision to use stale records.
It won’t be much of a hassle at home. As it is affecting mostly the Ubiquiti access points I can arrange
for them to use the misbehaving bind, and the rest of the network to use different servers.
Borja.
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