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?
Howdy,
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.