In troubleshooting, which approach works from the physical connection upwards?

The Bottom Up Approach is characterized by starting the troubleshooting process at the most basic level, which is the physical connection, and then moving upwards through the various layers and components of a system. This approach is particularly useful when dealing with connectivity issues, as it allows the technician to ensure that the fundamental connections (like cables and hardware) are functioning properly before addressing higher-level software or configuration settings.

Beginning with the physical layer ensures that any hardware problems are identified and resolved first, which can help to isolate issues more effectively. Once the physical connections are confirmed to be operational, the troubleshooting can then progress to the data link layer, network layer, and so on, until the problem is fully diagnosed. This method is systematic and thorough, reducing the risk of overlooking basic faults that can complicate troubleshooting efforts later in the process.