DHCP Is Dynamic Host Configuration  protocol It Will Provide Dynamic Address To Network Devices

DHCP Attacks Can Be Classfied Into Several Types

DHCP Snooping : Create Fake DHCP Server And Provide Ip Address To Network Devices  Even Real DHCP Server Not Able Respond On These Time There Are SO Many Tools Create DHCP Fake Server In Linux Pentest Os We Can Create Fake DHCP Server With Few Commands And The Response (Working Functionality OF DHCP Server Very High (Very Fast To Offer DHCP Offer Packets)

So We Can Prevent These Type Of Attacks BY Enable Security Mechanism On Switch Is Called DHCP Snoping

COnfiguration

Conf t

ip dhcp snooping

ip dhcp snooping verfiy mac address (It Will Check mac address whether its fake or original

on interface configuration

ip dhcp snooping trust

Configures the interface as a trusted interface for DHCP snooping. The no option configures the port as an untrusted interface.

Follow The Link For Configuration

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/4_1/nx-os/security/configuration/guide/sec_nx-os-cfg/sec_dhcpsnoop.html