Troubleshooting Network Connectivity

Learn how to diagnose the source of network connectivity problems by troubleshooting each layer of a network, including physical media, DNS issues, Wi-Fi interference, and more.

Introduction

• Introduction
• What you should know
• Tools and software

1. Physical Layer Troubleshooting

• POTS failure
• Copper Ethernet failure
• Fiber interface failure

2. Data Link and Network Layer Troubleshooting

• Switching loop
• Duplicate addressing
• DNS/IP addressing issues
• Rogue DHCP
• Failed routes/routing loop

3. Transport Layer Troubleshooting

• Port already in use, netstat
• Test service connectivity, telnet/wireshark

4. Wi-Fi Troubleshooting

• Intermittent service

5. Proactive Troubleshooting

• NMS
• Probes

Conclusion

• Next steps