Packet Tracer Lab: Routing, DHCP & IP Helper

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Addressing Reference Sheet

Keep this open in a second tab — every step below points back to it.

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This is exactly the plan built into the topology you were given (matches the subnet labels already drawn on the canvas).

Router	Interface	Connects to	IP Address	Subnet Mask
R1	GigabitEthernet0/0/0	Switch1 (LAN)	192.168.10.1	255.255.255.0
R1	GigabitEthernet0/0/1	R2 (WAN)	192.168.100.1	255.255.255.0
R2	GigabitEthernet0/0/0	Switch2 (LAN)	192.168.20.1	255.255.255.0
R2	GigabitEthernet0/0/1	R1 (WAN)	192.168.100.2	255.255.255.0
R2	GigabitEthernet0/0/2	R3 (WAN)	192.168.110.1	255.255.255.0
R3	GigabitEthernet0/0/0	Switch3 (LAN)	192.168.30.1	255.255.255.0
R3	GigabitEthernet0/0/1	R2 (WAN)	192.168.110.2	255.255.255.0
R3	GigabitEthernet0/0/2	R4 (WAN)	192.168.120.1	255.255.255.0
R4	GigabitEthernet0/0/0	Switch4 (LAN)	192.168.40.1	255.255.255.0
R4	GigabitEthernet0/0/1	R3 (WAN)	192.168.120.2	255.255.255.0

Device	Setting	Value
Server0	Static IP	192.168.40.10
Server0	Subnet Mask	255.255.255.0
Server0	Default Gateway	192.168.40.1

PC0–PC7 get their IP addresses automatically — you won't type numbers into them, you'll just switch them to DHCP.

1

Set IP Addresses on All Four Routers

GUI only — no typing commands yet

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Before you start: Left-click a router once to open its window. Click the Config tab at the top of that window (not CLI, not Desktop). You'll see a list of interfaces on the left side of that window — this is where you'll do all your router IP work in this phase.

Router R1 (leftmost router)

Left-click R1, click the Config tab, then click GigabitEthernet0/0/0 in the left-hand list.

Click the On button next to Port Status so it turns green (this "turns on" the network cable for that port).

In the IP Address box type 192.168.10.1 — click the Subnet Mask box and it will fill in 255.255.255.0 automatically.

Click GigabitEthernet0/0/1 in the left list, click On, then set IP 192.168.100.1 / mask 255.255.255.0.

Router R2

Click R2 > Config tab > GigabitEthernet0/0/0. Turn Port Status On. Set IP 192.168.20.1 / mask 255.255.255.0.

Click GigabitEthernet0/0/1. Turn On. Set IP 192.168.100.2 / mask 255.255.255.0 (this faces R1).

Click GigabitEthernet0/0/2. Turn On. Set IP 192.168.110.1 / mask 255.255.255.0 (this faces R3).

Router R3

Click R3 > Config tab > GigabitEthernet0/0/0. Turn On. Set IP 192.168.30.1 / mask 255.255.255.0.

Click GigabitEthernet0/0/1. Turn On. Set IP 192.168.110.2 / mask 255.255.255.0 (faces R2).

Click GigabitEthernet0/0/2. Turn On. Set IP 192.168.120.1 / mask 255.255.255.0 (faces R4).

Router R4 (rightmost router)

Click R4 > Config tab > GigabitEthernet0/0/0. Turn On. Set IP 192.168.40.1 / mask 255.255.255.0.

Click GigabitEthernet0/0/1. Turn On. Set IP 192.168.120.2 / mask 255.255.255.0 (faces R3).

Quick check: every green link light between routers and switches on the main canvas should now be solid green (not red or blinking amber). If a link is still red, the Port Status on one end probably wasn't switched On.

2

Turn On RIP Routing

GUI only — tells each router which networks to share

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RIP is how the routers learn about networks they aren't directly connected to. You'll tell each router about the networks it does touch, and RIP automatically shares that information with its neighbors.

On each router: R1, R2, R3, and R4

Open the router, click Config tab, then click RIP under the ROUTING heading in the left-hand list.

In the Network box, type each directly-connected network for that router (see table below), clicking Add after every one.

Router	Networks to add in RIP
R1	192.168.10.0 192.168.100.0
R2	192.168.20.0 192.168.100.0 192.168.110.0
R3	192.168.30.0 192.168.110.0 192.168.120.0
R4	192.168.40.0 192.168.120.0

Quick check: give it 15–20 seconds after the last router is configured (RIP needs a moment to converge), then try clicking the envelope-shaped "Add Simple PDU" tool and sending a ping from R1's LAN interface icon to R4's LAN interface icon on the topology. If it fails immediately, double check every network number above was typed correctly.

3

Set Up Server0 as the DHCP Server

GUI only — one server, four separate address pools

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Step A — Give Server0 a static address

Left-click Server0, click the Desktop tab, then click IP Configuration.

Select Static. Enter IP Address 192.168.40.10, Subnet Mask 255.255.255.0, Default Gateway 192.168.40.1.

Step B — Build the four DHCP pools

Still on Server0, click the Services tab, then click DHCP on the left.

Make sure the DHCP Service switch is set to On.

Fill in the first pool exactly like the row for LAN1 in the table below, then click Save.

Click the Add button to start a new pool. Repeat for LAN2, LAN3, and LAN4, clicking Save after each one.

Delete the leftover default pool if Packet Tracer created one automatically (named serverPool) — select it and click Remove.

Pool Name	Default Gateway	DNS Server	Start IP Address	Subnet Mask
LAN1	192.168.10.1	0.0.0.0	192.168.10.10	255.255.255.0
LAN2	192.168.20.1	0.0.0.0	192.168.20.10	255.255.255.0
LAN3	192.168.30.1	0.0.0.0	192.168.30.10	255.255.255.0
LAN4	192.168.40.1	0.0.0.0	192.168.40.20	255.255.255.0

Why does LAN4 start at .20 instead of .10? Server0 itself is already using 192.168.40.10 as a static address. Starting the pool at .20 keeps DHCP from accidentally trying to hand that same address to a PC.

4

Configure IP Helper-Address CLI required

The one step that has to be typed — this is the DHCP relay

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Why CLI, and why now? DHCP requests start as a broadcast, and routers never forward broadcasts by default. PC0, PC2, and PC4 are on different networks than Server0, so without a little help their DHCP requests will hit R1, R2, or R3 and go no further. ip helper-address tells a router "if you see a DHCP broadcast on this interface, forward it directly to this one server address instead." There's no GUI screen for this command in Packet Tracer, so this is the only place you'll open a CLI window.

Apply this on R1, R2, and R3 only

R4 does not need this command — Server0 lives on R4's own LAN, so those DHCP broadcasts already reach it directly without any help.

Left-click the router, click the CLI tab. Click once inside the black terminal window and press Enter if you see a blank prompt.

Type the commands below exactly, pressing Enter after each line. Replace gigabitEthernet0/0/0 with the router's LAN-facing interface (that's the one connected to its own switch — see table in Phase 1).

Router> enable

Router# configure terminal

Router(config)# interface gigabitEthernet0/0/0

Router(config-if)# ip helper-address 192.168.40.10

Router(config-if)# exit

Router(config)# exit

Router# copy running-config startup-config

Repeat the exact same six commands on R2's CLI (LAN interface is gigabitEthernet0/0/0).

Repeat again on R3's CLI (LAN interface is gigabitEthernet0/0/0).

Typing tip: if you make a mistake mid-line, backspace works normally. If a line gets confusing, press Ctrl+C and start that line over — it won't break anything you already saved.

5

Switch All Eight PCs to DHCP

GUI only — this is the easy part

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Do this on PC0 through PC7 (all eight PCs)

Left-click a PC, click the Desktop tab, then click IP Configuration.

Select the DHCP button (instead of Static). Wait a second or two — the IP Address, Subnet Mask, and Default Gateway fields should fill themselves in.

Close the window and repeat for every remaining PC (PC0, PC1, PC2, PC3, PC4, PC5, PC6, PC7).

Quick check: PC0 and PC1 should receive addresses starting with 192.168.10., PC2/PC3 with 192.168.20., PC4/PC5 with 192.168.30., and PC6/PC7 with 192.168.40. If any PC shows 0.0.0.0 or an address starting with 169.254, the ip helper-address on that PC's router likely wasn't typed correctly — go back and re-check Phase 4.

6

Final Test — Ping PC0 to PC7

Prove the whole network actually works end to end

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Left-click PC7, click Desktop > IP Configuration, and write down its IP address (it will look like 192.168.40.2x).

Left-click PC0, click Desktop > Command Prompt.

Type ping followed by a space and PC7's IP address, then press Enter. Example: ping 192.168.40.22

You should see four Reply from... lines. If instead you see Request timed out, work back through the checklist — Phase 1 (IP addresses) and Phase 2 (RIP) are the most common culprits.

Lab complete when: PC0 can successfully ping PC7, and every checkbox above is checked. Nice work — you just built a routed, multi-VLAN network with centralized DHCP from scratch.