[Rspamd-Users] Huge amount of DNS errors

[neotok at protonmail.com]

Hi users@,

we are a mail provider running rspamd. We can see a significant amount of DNS errors in the log, for example:

2018-10-30 11:06:32 #21149(normal) <225fbe>; lua; emails.lua:55: Error querying DNS(jk853oapzk8tyfr3ua978zk7yj8heenb.email.rspamd.com): server fail
2018-10-30 11:06:33 #26237(normal) <e5a143>; lua; emails.lua:55: Error querying DNS(o6ym5a53c55twtc3gf5qzbg1wr6x5bqw.email.rspamd.com): server fail
2018-10-30 11:06:33 #10067(normal) <59a80d>; lua; emails.lua:55: Error querying DNS(i35ptpawe3g7urqstxnkobuyz834gjr8.email.rspamd.com): server fail
2018-10-30 11:06:33 #26237(normal) <3bd56c>; lua; emails.lua:55: Error querying DNS(of5f9rrtt1wcu86d79ab4iiyii6cnojh.email.rspamd.com): server fail
2018-10-30 11:06:33 #26237(normal) <3bd56c>; lua; emails.lua:55: Error querying DNS(of5f9rrtt1wcu86d79ab4iiyii6cnojh.email.rspamd.com): server fail
2018-10-30 11:06:33 #10067(normal) <244d71>; lua; emails.lua:55: Error querying DNS(fb78oqnydchqqfe7gyb6qxg5dhbqgfsd.email.rspamd.com): server fail
2018-10-30 11:06:33 #10067(normal) <244d71>; lua; emails.lua:55: Error querying DNS(yeee4ah4o9rrjigsinzfsjwadyco35ax.email.rspamd.com): server fail
2018-10-30 11:06:33 #10067(normal) <5bb5eb>; lua; emails.lua:55: Error querying DNS(771nb7pq61cut9c69t7nb993f7jxggs3.email.rspamd.com): server fail
2018-10-30 11:06:33 #10067(normal) <3311a9>; lua; emails.lua:55: Error querying DNS(xg6i7n8mnywojzi1hujdy6nu5z4gafbz.email.rspamd.com): server fail
2018-10-30 11:06:33 #10067(normal) <ddca78>; lua; asn.lua:69: error querying dns (226.74.241.91.asn.rspamd.com): server fail
2018-10-30 11:06:33 #26237(normal) <dab65a>; lua; emails.lua:55: Error querying DNS(xg6i7n8mnywojzi1hujdy6nu5z4gafbz.email.rspamd.com): server fail
2018-10-30 11:06:33 #21149(normal) <145f57>; lua; emails.lua:55: Error querying DNS(nsgj7f9kridh8p1s38jpttefh59kn71x.email.rspamd.com): server fail
2018-10-30 11:06:33 #26237(normal) <ba0305>; lua; asn.lua:69: error querying dns (20.74.241.91.asn.rspamd.com): server fail
2018-10-30 11:06:33 #10067(normal) <cbdd0b>; lua; emails.lua:55: Error querying DNS(xg6i7n8mnywojzi1hujdy6nu5z4gafbz.email.rspamd.com): server fail
2018-10-30 11:06:33 #10067(normal) <d2ffd1>; lua; asn.lua:69: error querying dns (209.242.10.106.asn.rspamd.com): server fail
2018-10-30 11:06:34 #26237(normal) <48ba64>; lua; asn.lua:69: error querying dns (28.233.149.153.asn.rspamd.com): server fail
2018-10-30 11:06:34 #21149(normal) <b01313>; lua; emails.lua:55: Error querying DNS(9ib6e5nythf6je166txsrazhjmzu5uea.email.rspamd.com): server fail
2018-10-30 11:06:34 #21149(normal) <b246bc>; lua; emails.lua:55: Error querying DNS(94tjiah4y93rjjokdgn9mzckr6698cm9.email.rspamd.com): server fail
2018-10-30 11:06:34 #26237(normal) <73fe3b>; lua; asn.lua:69: error querying dns (50.75.241.91.asn.rspamd.com): server fail
2018-10-30 11:06:34 #26237(normal) <73fe3b>; lua; emails.lua:55: Error querying DNS(o6ym5a53c55twtc3gf5qzbg1wr6x5bqw.email.rspamd.com): server fail
2018-10-30 11:06:34 #10067(normal) <ce126d>; lua; emails.lua:55: Error querying DNS(94tjiah4y93rjjokdgn9mzckr6698cm9.email.rspamd.com): server fail
2018-10-30 11:06:34 #26237(normal) <d82642>; lua; emails.lua:55: Error querying DNS(94tjiah4y93rjjokdgn9mzckr6698cm9.email.rspamd.com): server fail

We use the local DNS resolver pdns for our purposes, mostly in its stock configuration on Debian Stretch. This is our setting in rspamd:

dns {

    timeout = 1s;

    sockets = 16;

    retransmits = 5;

}

I already tried to maximize the amount of sockets, but this does not seem to fix this issue... if it is an issue at all... Is that a problem we see right now or can we just ignore it? It happens 24/7 and is filling our logs...

Best regards!