NXDOMAIN Resolvers

Wed Apr 20 15:42:28 UTC 2022

On Wed, Apr 20, 2022 at 8:39 AM William Herrin <bill at herrin.us> wrote:
> On Wed, Apr 20, 2022 at 8:00 AM Antonia Affinito <antoniaaffinito12 at gmail.com> wrote:
>>
>> I noticed that, in case of a malicious domain name, some local resolvers send an NXDOMAIN and others a courtesy page address. Do you know if the resolvers (for example TIM, Wind or Fastweb) can return an NXDomain in order to protect their clients?
>
> From a network engineering perspective, any resolver that responds to an authoritative NXDOMAIN by generating an address for a courtesy page -is- the malicious actor. Doubly so if they lie about the DNSSEC status in the response.

Nevermind; I misunderstood your question. The domain name exists but
the resolver has blocked it. How should the resolver alter its
response: NXDOMAIN or the IP address of a courtesy web page explaining
the block.

Regards,
Bill Herrin

-- 
William Herrin
bill at herrin.us
https://bill.herrin.us/