I have a router with two WAN connections from different ISPs. When I query for a domain from ISP-A I get a completely different reply, from when I query for the same domain from ISP-B.

I am beginning to think that one of them is rerouting the traffic from and to their own DNS servers to avoid carrying that bandwidth on their main pipes. So changes made to the IP of a domain would not show up as quickly on the one that is re-routing the traffic I suppose.

If the ISP won't do anything about it, is there anyone to complain to like maybe ICANN or LACNIC or ARIN? Who regulates ISPs? How would I go about gathering evidence? DIG screen captures?

  • 4
    Is that your domain so you know that one reply is invalid? (because in many cases it is perfectly normal for a hostname to be resolved to different ip address depending on source address/isp) – Dusan Bajic Dec 11 '17 at 18:05
  • In 2017, dns is not such a significant fraction of the internet traffic any more. If your ISP is intercepting domain name queries, he is doing it for control, not efficiency. – anx Dec 11 '17 at 19:53
  • @DusanBajic Yes, I make a change and on one provider begins to resolve almost instantly and on the other provider takes 40min to an hour to resolve to the same IP. – Frank Barcenas Dec 11 '17 at 22:23
  • Are you aware that Googles allows you to request flushing their cache (all but NS records)? This may help exclude some other causes for your observation. – anx Dec 12 '17 at 2:16
  • Vote with your wallet: if dissatisfied by a service, just go shopping to use another one. Of course more easy to say than to do, but this is the only solution that would bring you back really the server you want. – Patrick Mevzek Dec 12 '17 at 4:21

I know of zero countries in the world that have a regulatory body that both a) cares and b) has the power to penalize IP spoofing foul play.

The international organizations all lack b), and on federal level you probably wont be successful either, for example:

FCC (USA) is probably the most popular one, which does care to some degree and will gladly register your formal customer complaints, then recommend you deploy DNSSEC to mitigate security issues and admit that they have zero power over ISPs.

Bundesnetzagentur (Germany) which falls into the "has the power" group (they do prosecute phone number spoofing, low internet speed, illegal ToC) has recently (in a similar case) expressly told me that they could not care less.

So what can you do?

  • Some ISPs are well known to do this and more or less openly admit under what circumstances they do. You are likely to be able to change your contract to avoid it (e.g. most ISPs have separate end user and business contracts, the latter including fewer shenanigans).
  • German DSL ex-monopolist Telekom Deutschland has as of April 2019 stopped providing spoofed responses, apparently shortly after learning about criminal investigation proceedings about data manipulation & formal complaints on privacy grounds. They had been redirecting customers to advertising partners by supplying fake A records. Since potential sanctions from privacy violations are currently hard to estimate for companies, the threat from such provisions in GDPR etc. might be enough.

That being said, you do not know for sure your ISP is doing that yet, your test is inadequate, the speed at which queries are updated is not deterministic, not even for googles (which obviously is NOT a single machine, and does not necessarily run the same setup for every machine, see https://peering.google.com/). Some equally inadequate (because only catching a few special cases) tests are:

  • Google goes SERVFAIL for dig version.bind chaos txt @, but caching resolvers in between will often respond (usually something borderline rude).
  • Query for a domain name that isnt properly encoded or otherwise invalid in its respective TLD (dig 🖕.com. in TXT @ - Google will say NXDOMAIN, other resolvers will say SERVFAIL.
  • If your ISP is doing it for all and any DNS queries, not just the google ones, you might verify by setting up a simple dns resolver (something like dnsmasq --no-resolv --server /example.com/ --bind-interfaces --listen-address --log-queries) and then look who is querying it when you access it via different ISPs (dig example.com @ The most obvious clue would then be that while you queried your server directly, you have received more responses than queries showed up in your resolver log (this is how i determine if i am being MitM'd by a caching resolver).

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