Which Troubleshooting Approach?

About this interactive

The lesson's approaches: - **Bottom-up:** Layer 1 first (the link light, the cable), then Layer 2, then Layer 3, up to the application. - **Top-down:** Layer 7 first (the app, name resolution), working down to the cable. - **Divide and conquer:** start at a middle layer, often with a ping at Layer 3; if it works, the fault is above it, if not, below. - **Follow the path:** test each device along the route, hop by hop, until the traffic stops. - **Substitution:** swap a suspect part for one known to be good (a power cord, power supply, fan or cable). - **Comparison:** compare the broken device's configuration or statistics with a working device or its own past baseline. The lesson's seventh approach, the **educated guess**, is not a bin here: any test can start from a guess, so a card for it would fit another bin too.

What you'll learn

Identify the troubleshooting approach a technician is using from what they test and in what order: bottom-up, top-down, divide and conquer, follow the path, substitution or comparison
Distinguish the three OSI-model approaches by where testing starts: the physical layer, the application layer or a middle layer

Aligned to

CompTIA Network+

5.1 Explain the troubleshooting methodology.

Cisco CCST Networking

5.1 Demonstrate effective troubleshooting methodologies and help desk best practices.

Key terms

Bottom-Up Troubleshooting: A troubleshooting approach that begins at Layer 1 (Physical) of the OSI model and works upward through each layer to isolate a network issue.
Top-Down Troubleshooting: A troubleshooting approach that begins at Layer 7 (Application) of the OSI model and works downward through each layer to isolate a network issue.
Divide and Conquer: A troubleshooting approach that starts testing at a middle OSI layer and narrows the problem scope upward or downward based on results.
Follow the Path: A troubleshooting approach that traces network connectivity hop by hop along the route between two devices to identify where a break occurs.
Comparison: A troubleshooting approach that contrasts the configuration or performance statistics of a malfunctioning device against a known-good device to identify discrepancies.
Open Systems Interconnection Model: A conceptual framework that standardizes network communication into seven distinct layers.

Topics

Troubleshooting Osi Model Troubleshooting Approaches Interactive Categorize

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