The Company network needs to enhance the reliability of the network. Which of the following
protocols provides network redundancy for IP networks, ensuring that user traffic
immediately and transparently recovers from first-hop failures in network edge devices or
access circuits, as defined by RFC 2281?

A.
STP

B.
IRDP

C.
ICMP

D.
HSRP

E.
None of the other alternatives apply

Explanation:
HSRP is defined in RFC 2281. The Hot Standby Router Protocol, HSRP, provides a
mechanism which is designed to support non-disruptive failover of IP traffic in certain
circumstances. In particular, the protocol protects against the failure of the first hop router
when the source host cannot learn the IP address of the first hop router dynamically. The
protocol is designed for use over multi-access, multicast or broadcast capable LANs (e.g.,
Ethernet). HSRP is not intended as a replacement for existing dynamic router discovery
mechanisms and those protocols should be used instead whenever possible. A large class
of legacy host implementations that do not support dynamic discovery are capable of
configuring a default router. HSRP provides failover services to those hosts.
Reference: http://www.faqs.org/rfcs/rfc2281.html