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Lab 19·Advanced

Mixed Network Troubleshooting Challenge

50–60 min20 Questions

Skills Tested

  • Diagnose Layer 2 and Layer 3 connectivity problems
  • Interpret routing, VLAN, ARP, and interface output together
  • Identify subnetting and default gateway issues
  • Troubleshoot OSPF neighbor and route learning problems
  • Diagnose DHCP, DNS, and NAT failures
  • Recognize ACL-related traffic blocking
  • Apply a structured multi-step troubleshooting process
Progress0%

You are assisting with a branch office network that has several simultaneous problems.

Reports:

  • !Some PCs can reach local devices but not remote devices
  • !Some VLAN users cannot reach servers in other VLANs
  • !Internet access is failing for some hosts
  • !Name resolution works inconsistently
  • !One application server is unreachable from a specific subnet

Analyze the available information and determine the most likely root cause in each case. This lab simulates a real mixed troubleshooting challenge.

Network Topology
Troubleshooting Lab
💻PC-AVLAN 10 .10.10
💻PC-BVLAN 20 .20.10
🔀S1trunk G0/1
🌐R1.10.1 | .20.1 | .12.1
🌐R2.12.2 | .30.1 | NAT
🖥️Server192.168.30.10
R1↔R2 link10.0.12.0/30
NAT on R2Inside → 203.0.113.5
Troubleshooting
Q1/20

PC-A can ping 192.168.10.1 (its default gateway) but cannot ping 192.168.30.10 (the remote server). What is the FIRST major area you should check?

Progress0 correct
Q1Q20

Lessons Reinforced

Lessons 4–11: Switching, ARP, IPv4, Routing, VLANs, OSPF, IP Services, ACLs