The network troubleshooting methodology is a systematic process of identifying and resolving network problems. It consists of eight steps:
1. Identify the problem.
2. Establish a theory of probable cause.
3. Test the theory to determine the cause.
4. Establish a plan of action to resolve the problem and identify potential effects.
5. Implement the solution or escalate as necessary.
6. Verify full system functionality and, if applicable, implement preventive measures.
7. Document findings, actions, and outcomes.
8. Write the lessons learned.
The last step, writing the lessons learned, is important for improving the network troubleshooting skills and knowledge. It involves reviewing the entire troubleshooting process, analyzing the root cause of the problem, evaluating the effectiveness of the solution, and identifying any best practices, tips, or tools that can be used for future reference. Writing the lessons learned can also help to update the network documentation, policies, and procedures, and share the experience and feedback with other network professionals

Explanation
A layer 2 switch is a device that forwards traffic based on MAC addresses within a single network segment or VLAN. A layer 2 switch is best suited for use at the access layer in a three-tier architecture system. The access layer is the layer that connects end devices such as computers, printers, and phones to the network. A layer 2 switch can provide fast and efficient switching for end devices without adding complexity or overhead to the network. References: https://www.comptia.org/training/books/network-n10-008-study-guide (page 139)

Traffic policing is the most appropriate for enforcing bandwidth limits when the performance of an application is not affected by the use of buffering but is heavily impacted by packet drops. Traffic policing is used to enforce predetermined data rate limits by discarding excess traffic that is sent beyond the set limit. Traffic shaping is used to manage the rate of data flow by buffering traffic that exceeds the set limits, while traffic marking is used to identify and differentiate traffic according to its type or priority. Traffic classification is used to identify different types of network traffic and assign them to different classes for different levels of treatment.

In the past, collisions (which were eliminated with full-duplex Ethernet decades ago) were likely causes of runts. Nowadays, bad wiring and electrical interference are leading causes of runts.