The suggested answer is A, C.
DNS-layer security primarily focuses on preventing threats and enforcing security policies based on DNS analysis. Live threat intelligence helps in identifying and mitigating threats as they occur, which is a core functionality of DNS-layer security. URL filtering is another core functionality, allowing the system to block or allow access to specific domains based on security policies. Proxy and file inspection, real-time sandboxing, and data analytics are more associated with broader security measures and not specifically confined to DNS-layer security.