problem resolving cdn.darkserv.net

[A. Schulze]

Hello,

unbound-1.14.0 (as well as 1.13.2) can't revolve cdn.darkserv.net.
I seen lots of the folloging messages (verbose: 2)

Dec 13 12:44:53 unbound[22:0] info: query response was THROWAWAY
Dec 13 12:44:53 unbound[22:0] info: response for cdn.darkserv.net. A IN
Dec 13 12:44:53 unbound[22:0] info: reply from <darkserv.net.> 144.217.187.53#53
Dec 13 12:44:53 unbound[22:0] info: query response was THROWAWAY
Dec 13 12:44:54 unbound[22:0] info: response for cdn.darkserv.net. A IN
Dec 13 12:44:54 unbound[22:0] info: reply from <darkserv.net.> 2001:41d0:2:aa69::53#53

I think, the nameservers itself have some kind of "edns-problem" but i don't understand it in detail.

zonemaster.net and EDNS Compliance Tester report different results for the same servers
or I simply don't see the difference...

darkserv.net:

- https://zonemaster.net/result/09db767380529a57
- https://ednscomp.isc.org/ednscomp/ee95621712

the same 4 servers are also authoritative for cdn.darkserv.net
and now there are no EDNS errors !?

- https://zonemaster.net/result/3f585012c88f40b9
- https://ednscomp.isc.org/ednscomp/b3bfd09b8b

anyway: this is my unexpected problem:

$ kdig @127.0.0.1 cdn.darkserv.net.
;; ->>HEADER<<- opcode: QUERY; status: SERVFAIL; id: 39664
;; Flags: qr rd ra; QUERY: 1; ANSWER: 0; AUTHORITY: 0; ADDITIONAL: 0

;; QUESTION SECTION:
;; cdn.darkserv.net.            IN      A

;; Received 34 B
;; Time 2021-12-13 12:44:51 CET
;; From 127.0.0.1 at 53(UDP) in 2690.9 ms

any ideas?

Andreas