How can I find out which server the DNS redirect is going through?

Question

Computer networks

Here is the BlockCheck result result of my provider:

[✓] DNS records are not replaced
[☠] DNS is redirected
[!] Result:
[⚠] Your ISP redirects third-party IPv4 DNS servers to its own, but does not replace DNS records.
This is somewhat odd and is common on mobile networks.
If you want to use a third party DNS, you should use an encrypted channel to the DNS servers, such as VPN, Tor, HTTPS/Socks proxies, or DNSCrypt, but this won't help bypass blocking.

As I understand it, the provider intercepts all requests to DNS, and then accesses the DNS server specified in my settings on its own behalf. That is, requests to the final DNS server come from some provider's servers. Question: how to find out the ip of these servers?

Answer 1

Unprepared in any way, if it is as described, then you can raise your dns server and send a request to it, see from whom it came, but according to the description it is some kind of nonsense. It looks more like a caching proxy with a cache function for dns traffic, including without any malicious intent. It is used by almost all moderately large providers to reduce external traffic. they have to pay for it (if they didn't know).
The cache can even be just on the nearest router in the case of a small provider. I’ll even say more that there is a cache in almost every home router.
Even if these servers look directly to the Internet (very unlikely), then what will this information give you?