In PAN-OS 10.0 and later, DNS Security allows policy actions to be applied based on three domains: command and control (C2), malware, and grayware. These domains are critical for identifying and mitigating security threats stemming from malicious activities. Command and control domains refer to servers that hackers use to maintain communications with compromised devices within a network. Malware domains are associated with known malicious software that can infect and compromise systems. Grayware domains represent potentially unwanted applications that might not be as harmful as malware but can still pose security risks.