Which netstat parameter displays all active TCP connections as well as UDP ports the computer is listening on?

The correct parameter to display all active TCP connections and UDP ports that the computer is listening on is indeed the one associated with the "a" option. Using this parameter with the netstat command provides a comprehensive view of both incoming and outgoing connections. When you execute netstat with this option, it reveals all sockets—both established connections and those in a listening state, thus giving insight into the network activity of the system.

Understanding the other parameters can provide additional context: the "-o" option displays the owning process ID associated with each connection, which offers more detail but does not focus strictly on active connections and listening ports. The "-n" parameter shows addresses and port numbers in numerical form instead of resolving them to names, providing a more straightforward representation but lacking the full view of connectivity states. The "-p" option can be used to show connections for a specific protocol, like TCP or UDP, but on its own, it wouldn't display all active connections or listening ports.

Thus, the "a" option is uniquely suited for highlighting all of the necessary information regarding active TCP connections and listening UDP ports, making it the most appropriate choice for the question.