[dns-operations] Strange behavior of google public resolver

[Taras Heichenko]

    Hi all!

I see the strange behavior of 8.8.8.8 resolver. I think that something wrong with domain but I see such
behavior only from 8.8.8.8 resolver. I try to ask about the public domain rv.ua.
And sometimes I get answer

koala:~ tasic$ dig @8.8.8.8 rv.ua ns

; <<>> DiG 9.10.6 <<>> @8.8.8.8 rv.ua ns
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55987
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;rv.ua.				IN	NS

;; ANSWER SECTION:
rv.ua.			17879	IN	NS	ns5.dnsmadeeasy.com.
rv.ua.			17879	IN	NS	ns6.dnsmadeeasy.com.
rv.ua.			17879	IN	NS	ns7.dnsmadeeasy.com.
rv.ua.			17879	IN	NS	ba1.ns.ua.

;; Query time: 37 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Thu Apr 18 11:33:43 EEST 2019
;; MSG SIZE  rcvd: 124

But much more often I get SERVFAIL
koala:~ tasic$ dig @8.8.8.8 rv.ua ns

; <<>> DiG 9.10.6 <<>> @8.8.8.8 rv.ua ns
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 25218
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;rv.ua.				IN	NS

;; Query time: 67 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Thu Apr 18 11:33:43 EEST 2019
;; MSG SIZE  rcvd: 34

I cannot understand why. Can anybody give me some clue what should I ask 8.8.8.8 to
understand what's wrong?

P.S. The domain is signed but by very old algorithm. And recently there were changed NSes but
without changing the DNSKEY RR and the DS in parent domain.

--
Best regards

Taras Heichenko
tasic at hostmaster.ua