DHCP-Snooping is a security feature in Catalyst Switches. It filters untrusted dhcp-messages and protects clients from peering up with an unauthorized DHCP server.
Config example:
Turn on snooping (global command)
Switch(config)# ip dhcp snooping
Switch(config)# ip dhcp snooping vlan [name]
Port-Configuration of DHCP server
Switch(config)# interface GigabitEthernet x/x
Switch(config-if)# ip dhcp snooping trust
Switch(config-if)# ip dhcp snooping limit rate 100