In this hands-on lab, you'll learn a structured approach to troubleshooting network issues. Network problems can be complex and frustrating, but by following a methodical approach, you can quickly identify and resolve issues. In this lab, you'll learn how to define the problem, identify affected systems, isolate the issue, and use a variety of tools to troubleshoot and resolve common network problems.

Throughout this lab, you'll work through a series of exercises that will help you develop your network troubleshooting skills. You'll learn how to use tools like ping, traceroute, and Wireshark to diagnose network issues, and how to troubleshoot problems at different layers of the network (physical, data link, and network).
By the end of this lab, you'll be able to:
  • Define a network problem and identify affected systems
  • Use a variety of tools to troubleshoot network issues
  • Troubleshoot problems at different layers of the network
  • Resolve common network problems
Let's get started

Lab Questions and Answers: 1.1 Core Concepts

1. What is the first step in troubleshooting network issues?

A. Check network configurations.

B. Define the problem.

C. Isolate the problem.

D. Identify affected systems.

Answer: B

2. Which of the following are examples of common network troubleshooting tools?

(select all that apply)

A. Ping

B. GNS3

C. Cable testers

D. Wireshark

E. OpenVAS

Answer: A, C, D

3. Which of the following issues are you likely to encounter at Layer 1?

(select all that apply)

A. Outdated MAC address tables.

B. Incorrect IP addresses.

C. Issues with individual switch ports.

D. Name resolution issues.

E. Hardware failure on the NIC.

F. Expired DHCP leases.

Answer: C, E

4. Which of the following issues are you likely to encounter at Layer 2?

A. Outdated MAC address tables.

B. Incorrect IP addresses.

C. Issues with individual switch ports.

D. Name resolution issues.

E. Hardware failure on the NIC.

F. Expired DHCP leases.

Answer: A

Lab Questions and Answers: 1.2 Guided Exercise

1. What is the response to your first attempt to ping google.com from Linux-A?

Answer: ping: bad address 'google.com'

2. What messages show at your initial log-in to Linux-B?

(select all that apply)

A. started, v1.30.1

B. sending discover

C. started, version1.30.1

D. DHCP failed. Please retry

E. failed to get a DHCP lease

F. no lease, forking to console

Answer: A, B, E

3. What is the name of the smb share on FILESERVER?

Answer: cybrary

4. On the IPsec status page, after connecting the P1 and P2 tunnels, what is the fourth algorithm listed in the Algo column?

Answer: MODP_2048

Lab Questions and Answers: 1.3 Challenge Exercise

1. What is the flag for this challenge?

Answer: TheFixer!

Conclusion

Congratulations on completing the Network Troubleshooting Lab In this lab, you used a structured approach to troubleshoot and resolve a variety of network issues on a pair of IPsec connected networks.
You started by troubleshooting SMB share connectivity on Linux-A, where you discovered a name resolution issue and configured the local DNS server to resolve the problem. You then moved on to troubleshoot internet connectivity on Linux-B, where you found that the DHCP server was not enabled on the firewall and configured it to provide IP addresses to clients.

Next, you returned to Linux-A to troubleshoot SMB share connectivity again, where you discovered that the local DNS server was not configured to resolve the FILESERVER hostname. You added an A record to the DNS server and configured the Linux-A client to use the local DNS server.

Finally, you troubleshooted VPN connectivity on Linux-B, where you discovered that the IPsec tunnel was disconnected and re-established the connection using the pfSense firewall configurator.