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How do I enable DHCP snooping on a Cisco switch?

The minimum configuration steps for the DHCP snooping feature are as follows:

  1. Define and configure the DHCP server.
  2. Enable DHCP snooping on at least one VLAN.
  3. Ensure that DHCP server is connected through a trusted interface.
  4. Configure the DHCP snooping database agent.
  5. Enable DHCP snooping globally.

What is DHCP snooping configuration?

DHCP snooping is a security feature intended to prevent rogue DHCP server from sending malicious DHCP replies. When DHCP snooping is enabled, the switch intercept all the DHCP requests, and discards DHCP replies coming from “untrusted” ports.

How does Cisco DHCP snooping work?

The DHCP snooping feature updates the database when the switch receives specific DHCP messages. Each entry in the DHCP snooping binding database includes the MAC address of the host, the leased IP address, the lease time, the binding type, and the VLAN number and interface information associated with the host.

How does IP DHCP snooping work?

When enabled on a VLAN, DHCP snooping stands between untrusted ports (those connected to host ports) and trusted ports (those connected to DHCP servers). A VLAN with DHCP snooping enabled forwards DHCP request packets from clients and discards DHCP server reply packets on untrusted ports.

What is DHCP snooping and how it works?

DHCP Snooping is a layer 2 security technology incorporated into the operating system of a capable network switch that drops DHCP traffic determined to be unacceptable. DHCP Snooping prevents unauthorized (rogue) DHCP servers offering IP addresses to DHCP clients.

How do I disable IP DHCP snooping?


  1. Enter system view.
  2. Enter interface view.
  3. Disable DHCP snooping on the interface. dhcp snooping disable. By default: If you enable DHCP snooping globally or for a VLAN, DHCP snooping is enabled on all interfaces on the device or on all interfaces in the VLAN.

What are the benefits of DHCP snooping?

Should I use DHCP snooping?

To address the concerns, DHCP Snooping, one of the protection mechanisms can prevent the invalid DHCP addresses from the rogue DHCP server and can ward off the resource-exhausting attack that attempts to use up all existing DHCP addresses.

What data does DHCP snooping collect?

DHCP snooping stores its observations in a database containing the client MAC address, DHCP assigned IP address, remaining lease time, VLAN, and switchport. The database is a simple flat-file that can be stored in device flash.

What traffic will DHCP snooping drop?

Here is a list of the type of traffic DHCP Snooping will drop: DHCP Snooping will drop DHCP messages DHCPACK, DHCPNAK, DHCPOFFER originating from a DHCP server that is not trusted – that is, connected to an untrusted port.

Is there a way to enable or disable DHCP snooping?

By default, DHCP snooping is disabled on all VLANs. Ensure that the DHCP server is connected to the switch using a trusted interface. You can enable or disable the DHCP snooping feature on the switch. By default, DHCP snooping is disabled. If you disable the DHCP snooping feature, all DHCP snooping configuration is lost.

Is the 2950 a layer 2 Cisco switch?

The 2950 is a layer 2 switch and as such it does not support DHCP. If the2950 connects to a layer 3 device for intervlan routing you may be able to configure DHCP on the layer 3 device. But it will not work on the 2950. HTH

How many bindings can be stored in DHCP snooping?

DHCP snooping has the following configuration guidelines and limitations: The DHCP snooping database can store 2000 bindings. DHCP snooping is not active until you enable the feature, enable DHCP snooping globally, and enable DHCP snooping on at least one VLAN.

How do I add DHCP to my Cisco switch?

In the IP configuration option, select the Static option and set the static configuration. The following image shows this procedure. Click the Services menu icon and click the DHCP Service in the left pane and select the on option in the right pane. Set the value in the DHCP Pool Options and click the Add button.