Troubleshooting data networks can be more efficient when analyzing what layer of the OSI model is showing problematic symptoms. To apply the OSI model in your troubleshooting efforts, you need to thoroughly understand what tasks are accomplished at each layer.

Identify which OSI layer is most relevant to the problem described in each scenario.

Physical layer				A downloaded file is corrupted due to missing data.
Network layer				Rats chew through a critical network cable.
Application layer				Your Web browser can't find a particular Web server and reports a routing error.
Transport layer				Your web browser freezes and is nonresponsive.