Which three protocols have been developed for IP routing redundancy to protect against first-hop router failure? (Choose three.)

A.
GLBP

B.
ICMP

C.
MSTP

D.
HSRP

E.
VRRP

F.
NHRP

Explanation:

If the gateway router for a subnet or VLAN goes down, packets have no way of being forwarded off the local subnet. Several protocols (GLBP, HSRP,VRRP) are available that allow multiple routing devices to share a common gateway address so that if one goes down, another automatically can pick up the active gateway role.

Cisco Hot-Standby Router Protocol (HSRP):
1. Created by Cisco, for Cisco in 1994
2. Uses a default hello timer of 3 seconds with a hold timer of 10 seconds

Virtual Router Redundancy Protocol (VRRP)
1. Created by the IETF in 1999
2. Works between multiple vendors
3. Has faster timers than HSRP by default – hello of 1 second, hold timer of 3 seconds

Gateway Load Balancing Protocol (GLBP)
1. Created by Cisco, for Cisco in 2005
2. Identical features to HSRP, but allows an active-active connection that adds load-balancing features