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Module 12: Network Troubleshooting, 12.4 Symptoms and Causes of Network…

- - - - Use simple language that the user can understand, avoiding complex technical jargon.
      - Listen attentively to the user’s descriptions and take notes to help document the problem.
      - Empathize with the user, acknowledging their stress and offering reassurance that the problem will be addressed.
      - Ask the right questions, using both open-ended questions to gather detailed information and closed questions for specific details.
      - Confirm your understanding of the issue by repeating it back to the user, ensuring that both parties agree on the problem.
- - - - physical topology map shows the physical layout and connections of network devices, essential for troubleshooting physical issues. Logical topologies (IPv4 and IPv6) illustrate how devices communicate on the network, with details like IP addresses, VLANs, and routing protocols, which help in understanding data flow and network structure.
- - - - Cable analyzers are handheld devices used to test and certify copper and fiber cables. Advanced models diagnose issues like near-end crosstalk (NEXT) or return loss (RL), display crosstalk and impedance behavior, and offer PC software to upload data for generating reports.
    - - Portable network analyzers help troubleshoot switched networks and VLANs. They can identify switch ports, monitor utilization, discover VLAN configurations, track top network talkers, analyze traffic, and provide interface details. Data can be sent to a PC for further analysis.
    - - Cable testers check data communication cables for issues like broken wires, crossed wiring, and shorts. They range from simple continuity testers to advanced time-domain reflectometers (TDRs), which can pinpoint cable breaks by measuring the time it takes for signals to reflect. TDRs for fiber-optic cables are called OTDRs.
    - - offers hardware and software for performance analysis in switching and routing environments. It includes a browser-based interface for generating traffic reports, capturing and decoding packets, and tracking response times to diagnose application issues related to the network or server.
    - - Digital multimeters (DMMs) measure voltage, current, and resistance. In network troubleshooting, they are primarily used to check power supply voltage and verify if network devices are receiving power.
  - - - Knowledge Bases
        
        Vendor knowledge bases, combined with search engines, provide valuable experience-based information for network administrators. For example, Cisco's Tools & Resources page, available under the Support menu on their website, offers tools for Cisco hardware and software.
      - Baselining Tools
        
        Automation tools for network documentation and baselining assist with creating network diagrams, maintaining up-to-date hardware/software records, and measuring bandwidth usage efficiently. For more details, search for 'Network Performance Monitoring Tools.
      - Network Management System Tools
        
        Network management system (NMS) tools include monitoring, configuration, and fault-management tools. They allow continuous, automated monitoring of network devices, providing status, statistics, and configuration details for key devices. For more information, search for 'NMS Tools.
- - - - Application layer problems prevent services from being provided to application programs. A problem at the application layer can result in unreachable or unusable resources when the physical, data link, network, and transport layers are functional. It is possible to have full network connectivity, but the application simply cannot provide data.