Open the lab

[ YOUR LAB FILE ]

Download the starting topology, then work through the lesson in SwitchLab.

Download SwitchLab Lab (.swlab)

  1. Save the .swlab file without renaming its extension.
  2. Open SwitchLab. Import and export controls currently require a desktop-width window. On a smaller screen, Tools → Fit brings the topology into view.
  3. Select Import Sandbox (folder icon), choose the downloaded file, and confirm the device and cable counts below.
  4. 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 enable only when the prompt ends in >.
  5. 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 IPv4 addressing and static routing lessons.

Follow the CCNA study path · Browse all SwitchLab labs

Topology

Serve a Remote LAN through DHCP Relay: starting network imported into the SwitchLab sandbox.
Starting topology captured in SwitchLab. Select the image to view it at full size.

5 devices · 4 links

Scenario

The organization centralizes its USERS pool on R2. PC1 sits behind R1 on a separate broadcast domain. Configure R1 to relay requests to the approved server.

Objectives

  • Verify the approved DHCP pool and gateway option.
  • Obtain a valid client lease and prove routed delivery.
  • Verify relay placement on the client-facing interface.

CCNA blueprint

200-301 v1.1 objectives — this lab covers the following specific skills, not every subtopic in the domain.

  • 4.3 — Explain the role of DHCP in automatic addressing.
  • 4.6 — Configure and verify DHCP client and relay behavior.

Starting information

  • PC1 must remain a DHCP client on 10.10.10.0/24 with gateway 10.10.10.1. Reserve 10.10.10.1 through 10.10.10.19.
  • PC2 is the static remote test host at 10.20.20.20. Both intersite routes are already configured.
  • The approved USERS pool belongs on R2. R1 g0/0 must relay to R2 at 10.0.12.2.
  • The isolated lab has one DHCP client, so the first available lease is 10.10.10.20. A real shared pool may allocate a different valid address.
HostIPv4 addressMaskGateway
PC1255.255.255.0None
PC210.20.20.20255.255.255.010.20.20.1
RouterInterfaceIPv4 addressMask
R1g0/010.10.10.1255.255.255.0
R1g0/110.0.12.1255.255.255.252
R2g0/010.20.20.1255.255.255.0
R2g0/110.0.12.2255.255.255.252
Device / portDevice / port
R1 / g0/1R2 / g0/1
PC2 / eth0R2 / g0/0
PC1 / eth0SW1 / g0/1
SW1 / g0/8R1 / g0/0

Tasks

  1. Inspect PC1 with ipconfig /all, the approved server’s DHCP pool/binding output and the relevant router configuration. Record the initial symptom.
  2. Implement the approved pool or relay correction; keep PC1 in DHCP mode and preserve both static routes.
  3. On PC1 run ipconfig /renew, then ipconfig /all. Verify the /24 mask, gateway and non-reserved lease address.
  4. Ping 10.20.20.20 from PC1 and the leased 10.10.10.20 from PC2. Match PC1 to the server binding, save/export and verify after reload.

Useful commands

show running-config
show ip route
show ip dhcp pool
show ip dhcp binding
copy running-config startup-config

Progressive hints

Hint 1

Separate failure to obtain a lease from receiving a lease with incorrect options.

Hint 2

A client broadcast does not cross a router by itself; a remote server needs a relay and a usable return path.

Hint 3

Use the approved pool on R2, add ip helper-address 10.0.12.2 on R1 g0/0, then renew PC1.

Verification

  • PC1 leases 10.10.10.20/24 with gateway 10.10.10.1 in this isolated topology.
  • The server binding agrees with the client configuration.
  • PC1 and PC2 reach each other after renewal and after completed-network reload.

Solution / walkthrough

Show Solution

Use enable only from a > prompt; if already at #, begin with configure terminal.

R1

Relay the client broadcast from its LAN gateway to the reachable remote server. The remote pool and its return route already match the client subnet.

enable
configure terminal
interface g0/0
ip helper-address 10.0.12.2
end
copy running-config startup-config

PC1

Obtain a fresh lease after the server or relay change, then inspect ipconfig /all and test off-subnet delivery.

ipconfig /renew

Run every verification check above after the changes. A saved configuration alone does not prove packet delivery.

Previous lab

Repair an Incorrect DHCP Gateway Option

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