Domain spoofing - NS spoofing, how to treat?

Question

Nginx

Greetings! I hope you can help:
There is a server 93.170.48.61 and sites are located on it, now there is a substitution for 31.170.179.200
ww6.testtradedoubler.com -> from there it is already a redirect to
my other NS sites, the files are not infected ...
but now for 2 hours pings from PCs are different:
Below in the comments I give an example .
Unfortunately, I don’t administer the server (I don’t have skills), please tell me how to prohibit substitution?

Answer 1

You have only NS servers in the whois of the domain, and there are left (ns ? .tymo se nko-vona.com) NS records on them.
Probably, sometimes the DNS client trusts one data, sometimes others - load balancing.
Fix NS records on your NS servers.

Answer 2

[email protected]:~$ host -t NS tymoshenko-vona.com
tymoshenko-vona.com name server ns2.tymosenko-vona.com.
tymoshenko-vona.com name server ns1.tymosenko-vona.com.
Are the NSs yours?

Answer 3

Server:         8.8.8.8
Address:        8.8.8.8#53

Non-authoritative answer:
Name:   tymoshenko-vona.com
Address: 93.170.48.61

what is the problem? who replaces whom?