What is the function of DHCPv6 Guard?

DHCPv6 Guard is a security feature designed to protect a network from unauthorized (rogue) DHCPv6 servers. It works by inspecting DHCPv6 messages and blocking those that originate from untrusted sources, specifically preventing rogue DHCPv6 servers from providing invalid IP addresses or other configuration information to clients. The correct answer states that it "Blocks DHCPv6 messages from relay agents to DHCPv6 servers." This is accurate because DHCPv6 Guard can be configured to block specific message types (like Advertise or Reply) from untrusted sources, even if they appear to come via a legitimate relay agent, thus preventing rogue server responses from reaching clients. The incorrect options are: "Relays messages between DHCPv6 servers and clients or relay agents" describes the function of a DHCPv6 relay agent, not DHCPv6 Guard. "Allows DHCPv6 replies and advertisements from rogue DHCPv6 servers" is the opposite of DHCPv6 Guard's purpose. "Indicates that DHCPv6 clients are affected" is a consequence of a rogue server, not the function of the guard itself.