In which scenario would a DNS sinkhole be effective in preventing an attack?

A DNS sinkhole is a security mechanism that redirects malicious or unwanted domain name system (DNS) queries to a safe IP address, effectively acting as a trap for malicious traffic. The scenario where malware tries to resolve an unregistered domain name signifies that some form of analysis or evasion is occurring, and the malware is attempting to communicate with potentially harmful domains. In this context, a DNS sinkhole would be effective because it can intercept and contain those DNS queries, preventing the malware from successfully reaching the harmful site. This redirection can limit the malware's ability to propagate or execute its harmful actions, thereby protecting the network.

In contrast, the other scenarios do not align as closely with the DNS sinkhole concept. For instance, an attacker sniffing traffic to port 53 is engaging in passive reconnaissance rather than actively engaging with DNS responses, which would not be mitigated by a sinkhole. Meanwhile, excessive traffic on port 53 may indicate a denial-of-service (DoS) attempt but doesn't directly correlate with malicious domain resolution that a sinkhole targets. Lastly, compromised routing tables can lead to man-in-the-middle attacks, where a DNS sinkhole might not be effective against the underlying routing issues that are diverting traffic. Thus, the scenario involving