What is the purpose of the netstat -a command?

The netstat -a command serves to display the current status of network connections, specifically showing all active connections and listening ports on a computer. This includes information about both incoming and outgoing connections, allowing users to see which ports are open and what protocols are in use (e.g., TCP or UDP).

By providing a comprehensive overview of all connections, netstat -a helps in diagnosing connection issues, monitoring network traffic, and identifying unauthorized connections or services potentially running on the device. This functionality is particularly useful for network administrators in assessing the security posture of a system, as they can monitor for unexpected or suspicious activity on specific ports.

The other choices do not align with this functionality. Testing network speed involves different tools and commands designed to measure bandwidth and latency. Changing network IP configuration typically requires commands like ipconfig or ifconfig, depending on the operating system. Monitoring firewall activity usually involves dedicated firewall management tools or commands that review logs and rules, rather than the output of netstat -a.