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

A.
HSRP

B.
MSTP

C.
ICMP

D.
VRRP

E.
GLBP

Explanation:
A First Hop Redundancy Protocol (FHRP) is a computer networking protocol which is
designed to protect the default gateway used on a subnetwork by allowing two or more
routers to provide backup for that address; in the event of failure of the/an active router, the
backup router will take over the address, usually within a few seconds. In practice, such
protocols can also be used to protect other services operating on a single IP address, not
just routers.
Examples of such protocols include (in approximate order of creation):

Hot Standby Router Protocol (HSRP) – Cisco’s initial, proprietary standard
Virtual Router Redundancy Protocol (VRRP) – an open standard protocol
Gateway Load Balancing Protocol (GLBP) – a more recent proprietary standard from Cisco
that permits load balancing as well as redundancy