Which of the following protocols enables a group of routers to form a single virtual router,
and then use the real IP address of a router as the gateway address, as defined in RFC 2338?

A.
Proxy ARP

B.
HSRP

C.
IRDP

D.
VRRP

E.
GLBP

Explanation:
The Virtual Router Redundancy Protocol (VRRP) feature enables a group of routers to form
a single virtual router. The LAN clients can then be configured with the virtual router as their
default gateway. The virtual router, representing a group of routers, is also known as a
VRRP group. VRRP is defined in RFC 2338.
Reference: http://www.faqs.org/rfcs/rfc2338.html