DHCP Snooping

Question 1

What does DHCP Snooping?

Answer 1

DHCP Snooping only allows DHCP exchanges to take place across certain trusted ports, and prevents rogue DHCP servers.

Question 2

What is the default port state once DHCP snooping is enabled?

Answer 2

By default, all ports are considered un-trusted.

Question 3

What is the default action for DHCP snooping violations?

Answer 3

The offending port will be placed into err-disabled mode.

Question 4

What are the three steps in configuring DHCP snooping?

Answer 4

1. Enable DHCP snooping globally.
2. Enable which VLANs DHCP snooping will enforce.
3. Specify your trusted ports.

Question 5

What is the DHCP snooping validity check?

Answer 5

All DHCP discover/request packets will have the option 82 value replaced with the switch’s own value. If this value does not match on the DHCP replies, the packets are dropped.

Question 6

What is rate limiting?

Answer 6

Rate limiting sets how many DHCP packets are allowed across a trusted port per second.

Question 7

What is DHCP snooping necessary for?

Answer 7

Dynamic arp inspection and IP source guard.