and all subdomains while ensuring no packets from any internal client are sent to that site. Which type of policy must the network administrator use to accomplish this goal?

A Prefilter policy is used for initial traffic handling, such as fastpathing or blocking traffic based on specific characteristics, but it does not specifically prevent DNS resolution of a domain.

An SSL policy is used for decrypting and inspecting encrypted traffic, but it does not prevent the initial DNS lookup or the sending of packets to the destination.

A DNS policy can be configured to block DNS queries for specific domains and subdomains, preventing internal clients from resolving the malicious site's IP address. By blocking DNS resolution, clients cannot initiate any network connections, thus ensuring no packets are sent to that site.

An Access Control policy with URL filtering blocks traffic based on the URL, but this occurs after the DNS lookup has resolved and the client has attempted to establish a connection, meaning some packets would have already been sent.