Hi Martin, On 4/9/20 9:56 AM, Martin Kellermann via Pdns-users wrote: > I’m facing the fact, that sometimes the servfail-packets counter > increases and i would debug this and find the reason why PowerDNS sends > out a „servfail“ packet. > > Actually today the counter increased from 0 to 2 and i don’t know why! > > https://doc.powerdns.com/authoritative/performance.html#servfail-packets > tells me, that this is due to a database problem. > > https://doc.powerdns.com/authoritative/performance.html#ring-buffers > tells me that the servfail-queries ring-buffer shows which queries have > been causing servfails. > > But when i look at this ring-buffer (server:8081/?ring=servfail-queries) > there are no entries – it’s empty.
At a quick glance the only place in the code where we increase the 'servfail-packets' counter but do not add the offending query to the 'servfail-queries' ring-buffer is when we receive a query for a DNS name that has an 8-bit byte in it and '8bit-dns' [1] is not set (which is the default), so I assume that's what you are experiencing. Note that in that case we also increase the 'corrupt-packets' counter and place the offending query into the 'remotes-corrupt' ring-buffer, so you might be able to figure out what query caused this. Be aware however that there are other cases where we increase 'corrupt-packets' and insert into 'remotes-corrupt', like a QR or TC bit set in a query, or a query that we simply could not parse. [1]: https://docs.powerdns.com/authoritative/settings.html#bit-dns Best regards, -- Remi Gacogne PowerDNS.COM BV - https://www.powerdns.com/
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