Fast-Flux DNS is a technique used by attackers to hide phishing and malware distribution sites behind an ever-changing network of compromised hosts acting as proxies. It involves rapidly changing the association of domain names with multiple IP addresses, making the detection and shutdown of malicious sites more difficult. This technique contrasts with DNS zone transfers, which involve the replication of DNS data across DNS servers, or Dynamic DNS, which typically involves the automatic updating of DNS records for dynamic IP addresses, but not necessarily for malicious purposes. DNS interrogation involves querying DNS servers to retrieve information about domain names, but it does not involve hiding malicious content. Fast-Flux DNS specifically refers to the rapid changes in DNS records to obfuscate the source of the malicious activity, aligning with the scenario described.