Open the lab
[ YOUR LAB FILE ]
Download the starting topology, then work through the lesson in SwitchLab.
- Save the .swlab file without renaming its extension.
- Open SwitchLab. Import and export controls currently require a desktop-width window. On a smaller screen, Tools → Fit brings the topology into view.
- Select Import Sandbox (folder icon), choose the downloaded file, and confirm the device and cable counts below.
- Select a device, then choose Open device on desktop or its name in the bottom bar on smaller screens. Select CLI for switches/routers or Desktop → Terminal for PCs. Enter
enableonly when the prompt ends in >. - Follow this page beside the simulator. Use a free account to export your work. Reimport the original download to restart; export any work you want to keep first.
Prerequisites
- Complete the Ethernet fundamentals lessons.
- For the routed troubleshooting lessons, recognize connected and static routes.
Topology
4 devices · 3 links
Scenario
PC1 was restored from an image with the wrong addressing. The router-to-router path and both static routes are already correct. Repair the workstation to match its LAN.
Objectives
- Derive or verify IPv4 host and gateway settings against the approved subnet plan.
- Prove the intended local and routed paths after correcting configuration.
CCNA blueprint
200-301 v1.1 objectives — this lab covers the following specific skills, not every subtopic in the domain.
- 1.6 — Configure and verify IPv4 addressing and subnetting.
Starting information
- Approved PC1 settings: 10.10.10.10/24 with gateway 10.10.10.1. PC2 remains 10.20.20.20/24 with gateway 10.20.20.1.
- Keep router interfaces, static routes and cables unchanged. Use the addressing table to distinguish starter values from the approved repair.
- PC1 has both an incorrect address and an overly broad /16 mask. Correct both; an address-only repair can hide the mask error on this small topology.
| Host | IPv4 address | Mask | Gateway |
|---|---|---|---|
| PC1 | 10.10.99.10 | 255.255.0.0 | 10.10.10.1 |
| PC2 | 10.20.20.20 | 255.255.255.0 | 10.20.20.1 |
| Router | Interface | IPv4 address | Mask |
|---|---|---|---|
| R1 | g0/0 | 10.10.10.1 | 255.255.255.0 |
| R1 | g0/1 | 10.0.12.1 | 255.255.255.252 |
| R2 | g0/0 | 10.20.20.1 | 255.255.255.0 |
| R2 | g0/1 | 10.0.12.2 | 255.255.255.252 |
| Device / port | Device / port |
|---|---|
| PC1 / eth0 | R1 / g0/0 |
| R1 / g0/1 | R2 / g0/1 |
| PC2 / eth0 | R2 / g0/0 |
Tasks
- Run
ipconfig /allon PC1. Compare its address, mask and gateway with the approved plan. - Test PC1 → 10.10.10.1 and PC1 → 10.20.20.20. Use router
show ip routeoutput to separate a host issue from a missing route. - Apply only the approved PC1 settings with the PC terminal; leave the routers and PC2 unchanged.
- Verify the exact host address, mask and gateway, local-router delivery and both directions of intersite host traffic. Export/reload the completed network.
Useful commands
show ip route
copy running-config startup-configProgressive hints
Hint 1
Calculate the subnet boundary before changing an address. A gateway is used only for a destination outside the host subnet.
Hint 2
Compare all three settings—address, mask and gateway. A successful ping alone may not reveal an overly broad mask.
Hint 3
Use the first usable address for each requested gateway; for PC repairs, apply netsh ip set with the exact approved address, mask and gateway.
Verification
- The final addressing matches the approved plan exactly.
- All paths listed in the tasks succeed in both directions.
- The completed export retains the repaired addressing after reload.
Solution / walkthrough
Show Solution
Use enable only from a > prompt; if already at #, begin with configure terminal.
PC1
Restore the approved host settings. The default gateway must be a reachable router on PC1’s own subnet; it is not the remote host or remote router.
netsh ip set 10.10.10.10 255.255.255.0 10.10.10.1Run every verification check above after the changes. A saved configuration alone does not prove packet delivery.