How to Use This Page
Instructor flow: demonstrate the basic Packet Tracer interface first, then assign one lab at a time. Students should document symptoms, identify the likely OSI layer, fix the issue, and prove the fix.
- Build the topology exactly as shown.
- Apply the starting configuration.
- Test with ping, interface status, VLAN tables, or routing tables.
- Correct the issue and verify full functionality.
Topology built correctlyFault identifiedFix appliedVerification shownDocumentation completed
These labs align with Network+ topics including VLANs, routing, addressing, cabling, physical interfaces, and troubleshooting tools.
Scenario 1 — VLAN Switch Troubleshooting
Switch / VLANTwo departments use the same access switch. Sales PCs should communicate with other Sales devices, and IT PCs should communicate with other IT devices. One Sales PC cannot reach the Sales server.
- Sales VLAN: VLAN 10
- IT VLAN: VLAN 20
- PC-Sales-1 IP: 192.168.10.11 /24
- Server-Sales IP: 192.168.10.50 /24
- PC-Sales-1 cannot ping Server-Sales.
Instructor Answer
The likely issue is that Fa0/1 is assigned to the wrong VLAN. PC-Sales-1 and Server-Sales must both be in VLAN 10.
S1# show vlan brief S1# configure terminal S1(config)# interface fa0/1 S1(config-if)# switchport mode access S1(config-if)# switchport access vlan 10 S1(config-if)# no shutdown S1# show vlan briefVerification: PC-Sales-1 should ping 192.168.10.50 successfully.
Scenario 2 — Router Default Gateway Issue
Router / IP AddressingA small office has two networks connected through one router. Devices in each LAN can communicate locally, but the HR computer cannot reach the Accounting computer across the router.
- HR-PC can ping 192.168.30.1.
- Accounting-PC can ping 192.168.40.1.
- HR-PC cannot ping Accounting-PC.
- Accounting-PC default gateway is set to 192.168.30.1.
Instructor Answer
The Accounting-PC has the wrong default gateway. A host’s default gateway must be the router interface on its own local subnet.
Accounting-PC IP: 192.168.40.25 Subnet mask: 255.255.255.0 Correct default gateway: 192.168.40.1Verification: Ping from HR-PC to Accounting-PC and from Accounting-PC back to HR-PC.
Scenario 3 — Cable or Physical Interface Failure
Cable / InterfaceA workstation was moved to a new desk. It now shows no network connectivity. The switch port light is off, and the PC has an APIPA address.
- PC receives a 169.254.x.x address.
- Switch Fa0/7 shows down/down.
- Other users on the same switch are working.
- The issue started after the workstation was physically moved.
Instructor Answer
The symptoms point to a Layer 1 problem. The APIPA address indicates the PC did not receive a DHCP lease, and the switch port being down/down points to a physical connection issue.
S1# show interface fa0/7 Check: link status, cable seating, wall jack, patch panel, and patch cable. Use: cable tester or known-good cable.Verification: Link light returns, interface changes to up/up, and the PC receives a valid 192.168.50.x DHCP address.
Scenario 4 — Wireless Channel Interference
Wireless / PerformanceStudents complain that wireless connectivity drops in one classroom. The access point is working, but users experience high latency and intermittent disconnects.
- Strong signal near the AP.
- High latency and inconsistent throughput.
- Several nearby APs overlap the same 2.4 GHz channel range.
- Wired network connectivity is normal.
Instructor Answer
The issue is wireless interference caused by overlapping 2.4 GHz channels. A Wi-Fi analyzer should be used to view nearby networks and channel utilization.
Recommended fixes: - Use non-overlapping 2.4 GHz channels: 1, 6, or 11 - Move capable clients to 5 GHz or 6 GHz - Reduce channel width if needed - Adjust AP placement and power levelsVerification: Lower latency, fewer disconnects, cleaner channel usage, and stable client association.
Instructor Wrap-Up Questions
- Which OSI layer did each problem start with?
- What command or tool proved the problem?
- What command or test proved the fix?
- What should be documented after the lab?