A network link that is dropping packets can trigger EDNS failures in versions of
BIND before 9.13.3. These versions have code to compensate for servers that
fail to respond to EDNS queries or fail to respond to EDNS queries with DO=1
or fail to respond to queries with (particular) EDNS options set. BIND would
fallback to plain DNS queries to workaround these issues, but that broke
DNSSEC when the answers where coming from a signed zone and the packet loss
is due to network issues.
5029. [func] Workarounds for servers that misbehave when queried
with EDNS have been removed, because these broken
servers and the workarounds for their noncompliance
cause unnecessary delays, increase code complexity,
and prevent deployment of new DNS features. See
https://dnsflagday.net for further details. [GL #150]
> On 29 Jul 2020, at 09:10, <youssef.fassifi...@inwi.ma>
> <youssef.fassifi...@inwi.ma> wrote:
>
> Hi All,
>
> I am using Bind as resolver for end users .
>
> At various time, bind logs show "broken trust chain" continuously , for
> about 20mn ~ 30 mn causing an increase of "recursive clients" shown in "rndc
> status" and a decrease of "DNS sucess rate KPI" supervised from end users
> side. then the error disappear and everything is OK.
>
> the problem appears on different server at different time.
>
> What could be the problem?
>
> Regards,
>
>
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