While consulting release notes (B) is a good first step, and a dry run (A) is beneficial, the most effective and thorough method for validating no new network connections in a highly sensitive environment is to deploy in a controlled, isolated test environment and perform deep packet inspection (C). A full PCAP will capture all outbound connections initiated by the agent, allowing for granular analysis against documented FQDNs. Firewall logs (A) might miss connections to permitted but previously unobserved FQDNs or temporary connections. Vulnerability scanning (D) is about open ports, not necessarily outbound connection behavior. Trusting the vendor (E) is insufficient for high-security environments.