On a Windows system, which command-line tool would you use to discover which local port numbers your computer is currently listening on?

Introduction / Context:
When troubleshooting network problems or checking for unwanted services, administrators often need to know which ports a computer is listening on. On Windows, there are several network related commands, but only some of them provide port and connection information. This question tests whether you can identify the correct command-line tool for listing listening ports and local addresses.

Given Data / Assumptions:

• The operating system is Windows, using its standard command-line tools.
• We want to discover local port numbers and listening states, not just IP configuration or routing paths.
• Commands like ipconfig, tracert, and nslookup serve other purposes.
• We assume basic familiarity with TCP/IP networking concepts such as ports and sockets.

Concept / Approach:
The netstat command is designed to display network statistics, including active connections and listening ports. Using options such as -a, -n, and -o, you can see all listening TCP and UDP ports, addresses, and sometimes the process IDs associated with them. Other commands like ipconfig show IP configuration only, tracert traces routes, and nslookup performs DNS queries. Therefore, the correct answer must clearly point to netstat as the tool that reveals listening ports.

Step-by-Step Solution:
1. List what each candidate command does: ipconfig shows IP configuration, tracert traces the route to a host, nslookup performs DNS queries, and netstat shows network connections and listening ports.2. Identify which of these can show listening sockets and their port numbers.3. Netstat with options such as netstat -an on Windows will list all connections and listening ports numerically.4. Option A states that you should use netstat with appropriate options to list listening ports and associated addresses, which aligns with real usage.5. Option B incorrectly claims that ipconfig displays listening ports; in reality, it shows addresses, masks, and gateways.6. Option C confuses route tracing with port listing, which are different tasks.7. Option D incorrectly suggests that nslookup reveals open ports, but it only deals with DNS name resolution.8. Therefore, Option A is the correct answer.

Verification / Alternative check:
You can verify by opening a command prompt and running netstat -an. The output will show a list of local addresses and ports, foreign addresses, and states such as LISTENING or ESTABLISHED. Comparing this with the output of ipconfig, tracert, or nslookup makes it clear that only netstat provides detailed port and connection information.

Why Other Options Are Wrong:
Option B is wrong because ipconfig displays only configuration parameters, not detailed socket states.Option C is wrong because tracert focuses on network path discovery using ICMP or UDP, not on local listening sockets.Option D is wrong because nslookup communicates with DNS servers to resolve names and does not scan or list ports.

Common Pitfalls:
Some users mistakenly expect ipconfig to show everything about networking, including ports and connections, but it is limited to interface configuration. Another pitfall is forgetting to run the command with the right options; for example, without -a or -n, netstat might not show all the relevant details in numeric form. Learning to use netstat correctly is a basic but important skill for network troubleshooting.

Final Answer:
Use the netstat command with appropriate options to list listening ports and associated addresses.