Which protocol will enable a group of routers to form a single virtual router and will use the
real IP address of a router as the gateway address?
A.
Proxy ARP
B.
HSRP
C.
IRDP
D.
VRRP
E.
GLBP
Explanation:
The correct answer is VRRP whereby either a virtual or physical address can be chosen as
the gateway address. If the physical address of R2 is the gateway address, then R2 will
become the gateway. If R2 goes down, R3 (or R4 etc) will become the gateway and will
assume the IP address which, to it, will be a virtual one as none of its interfaces are
configured with that address. In this scenario, R2, R3 and R4 form one virtual router
whereby R1’s physical address is used as the gateway address. HSRP does not use
physical addresses for the gateway at all.
Reference:
Virtual Router Redundancy Protocol
(http://www.cisco.com/en/US/docs/ios/12_0st/12_0st18/feature/guide/st_vrrpx.html)