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Lesson 1 of 5

DHCP Snooping Configuration

Lab Objectives

  • Enable DHCP Snooping globally and for the VLAN carrying client hosts.
  • Configure switch ports as trusted or untrusted so only the legitimate DHCP server (R1) can send DHCP replies.
  • Verify clients obtain addresses from the DHCP server and validate snooping state.

Lab Tasks (Try It Yourself First!)

Complete these tasks WITHOUT looking at the solution below. Use ? and show commands to figure it out.

Task 1: Enable DHCP Snooping

Enable DHCP snooping globally on the switch and restrict snooping to VLAN 100 (the VLAN where PC-1 and PC-2 reside). Also disable inserting DHCP Option 82 information by the switch.

Task 2: Configure Trusted Ports

Configure the switch interface connected to the DHCP server (R1) as a trusted DHCP snooping port. Also mark the interface toward R3 (the device acting as a DHCP relay agent) as trusted.

Task 3: Force Client Renew

On PC-1 and PC-2, release the current DHCP lease and renew it so they request DHCP addresses again. Confirm they receive addresses from the DHCP server.

Think About It: If an attacker connects a rogue DHCP server on an untrusted port, what types of problems can arise in a production network? How does DHCP Snooping mitigate those?

Lab Solution

Topology (logical, exact interface names shown). R1 is the only DHCP Server in this lab.

                R1 (DHCP Server)
                E0/0 192.1.14.1
                    |
                 SW-100
             E0/0  |  E0/3
                PC-1 PC-2 (VLAN100 clients)

Notes:

  • Switch SW-100 has clients in VLAN 100.
  • R1 (E0/0) is the legitimate DHCP server.
  • R3 (E0/0) acts as DHCP relay; its switch-facing port must be trusted.

Task 1 Solution: Enable DHCP Snooping

What we are doing: We enable DHCP Snooping globally, limit snooping to VLAN 100 (so the switch only tracks DHCP messages for that VLAN), and disable the switch inserting DHCP information option (Option 82). Disabling Option 82 is required in this environment because the DHCP server (R1) does not support Option 82; if the switch inserts Option 82 and the server rejects it, clients will fail to get addresses.

SW-100(config)# ip dhcp snooping
SW-100(config)# ip dhcp snooping vlan 100
SW-100(config)# no ip dhcp snooping information option

What each command does and why it matters:

  • ip dhcp snooping — Enables DHCP Snooping globally on the switch. This activates the feature that inspects DHCP packets and builds a binding table (MAC ↔ IP ↔ VLAN ↔ port). Real-world: this prevents rogue DHCP servers from assigning addresses to clients.
  • ip dhcp snooping vlan 100 — Limits snooping to VLAN 100 so the switch only performs DHCP inspection for that VLAN. This reduces processing and matches the scope of protected clients.
  • no ip dhcp snooping information option — Stops the switch from adding DHCP Option 82 (relay agent information) into DHCP requests. We disable this because R1 does not support Option 82; if left on, DHCP replies might be rejected.

Verify:

SW-100# show ip dhcp snooping

Expected output (representative — includes critical lines you should see):

Switch# show ip dhcp snooping
DHCP snooping is enabled
DHCP snooping is configured on following VLANs:
    100
DHCP snooping is operational
Option 82 insertion is disabled


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cisco
SW-100(config)# interface E0/0
SW-100(config-if)# ip dhcp snooping trust
!
SW-100(config)# interface E0/3
SW-100(config-if)# ip dhcp snooping trust

What each command does and why it matters:

  • interface E0/0 followed by ip dhcp snooping trust — Marks the interface toward R1 as trusted so DHCP server responses are allowed. This is essential; otherwise legitimate server replies would be dropped.
  • interface E0/3 followed by ip dhcp snooping trust — Marks the interface toward R3 (DHCP relay) as trusted. A relay forwards server replies and requests; the switch must trust the relay.

Verify:

SW-100# show ip dhcp snooping trust

Expected output (representative):

Switch# show ip dhcp snooping trust
Trunk    VLAN  Ports
-------------------------
 100     E0/0
 100     E0/3


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text
C:\> ipconfig /release
C:\> ipconfig /renew

What this does and why it matters:

  • ipconfig /release — Tells the client to give up its existing IP lease and send a DHCPRELEASE (or simply clear the current lease locally).
  • ipconfig /renew — Causes the client to send a DHCPDISCOVER to obtain a new lease. This triggers DHCP packet flow through the switch so you can verify snooping behavior.

Verify client address and snooping binding: On PC-1 after renew:

C:\> ipconfig

Ethernet adapter Local Area Connection:

   IPv4 Address. . . . . . . . . . . : 192.168.1.10
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.1.1

On the switch, check the snooping binding to see the DHCP mapping:

SW-100# show ip dhcp snooping binding

Expected output (representative):

Switch# show ip dhcp snooping binding
MacAddress          IpAddress       Lease(sec)  Type       VLAN  Interface
------------------------------------------------------------------------
0011.2233.4455      192.168.1.10    8594        dhcp-snooping 100  FastEthernet0/1
0066.7788.99aa      192.168.1.11    8610        dhcp-snooping 100  FastEthernet0/2


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</div>

cisco
SW-100# show ip dhcp snooping
  1. Verify the uplink to the DHCP server is trusted:
SW-100# show ip dhcp snooping trust
  1. If the uplink is not trusted, enable it:
SW-100(config)# interface E0/0
SW-100(config-if)# ip dhcp snooping trust
  1. If Option 82 was enabled and the server does not support it, disable it:
SW-100(config)# no ip dhcp snooping information option

Explanation: If the server-side interface is untrusted, the switch will drop DHCP server responses. If the switch inserts Option 82 and the server rejects it, the lease will fail.

Verification Checklist

  • DHCP snooping enabled globally on the switch.
  • DHCP snooping configured for VLAN 100.
  • no ip dhcp snooping information option set because R1 does not support Option 82.
  • E0/0 and E0/3 on SW-100 configured as trusted.
  • Clients obtain addresses and appear in the snooping binding table.

Common Mistakes

SymptomCauseFix
Clients do not receive DHCP IPsUplink to DHCP server is not trusted; switch drops server repliesConfigure ip dhcp snooping trust on the interface toward the DHCP server
DHCP leases fail after switch Option 82 addedDHCP server does not support Option 82Configure no ip dhcp snooping information option
No entries in snooping binding tableDHCP snooping not enabled for the client VLANRun ip dhcp snooping vlan <vlan-id> and ensure snooping is enabled globally

Challenge Task

Protect the network further by enabling DHCP Snooping across two VLANs (VLAN 10 and VLAN 20) with different uplinks to legitimate DHCP servers. Configure the correct trusted ports and verify that bindings are maintained separately per VLAN. (No step-by-step — identify the VLANs, trusted uplinks, and commands needed.)

Final note: DHCP Snooping is a low-effort, high-impact feature for preventing rogue DHCP servers. In production networks it is commonly combined with dynamic ARP inspection and IP Source Guard to form a layered defense against L2-based spoofing and man-in-the-middle attacks.

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