Refer to the exhibit. HSRP has been configured and Link A is the primary route to router R4.
When Link A fails, router R2 (Link B) becomes the active router. Which router will assume
the active role when Link A becomes operational again?”
A.
The primary router R1 will reassume the active role when it comes back online.
B.
The standby router R2 will remain active and will forward the active role to router R1 only
in the event of its own failure.
C.
The standby router R2 will remain active and will forward the active role to router R1 only
in the event of Link B failure.
D.
The third member of the HSRP group, router R3, will take over the active role only in
event of router R2 failure.
Explanation:
HSRP election is based on a priority value (0 to 255) that is configured on each router in the
group. By default, the priority is 100. The router with the highest priority value (255 is
highest) becomes the active router for the group. If all router priorities are equal or set to the
default value, the router with the highest IP address on the HSRP interface becomes the
active router. To set the priority, use the following interface configuration command:
Switch(config-if)# standby group priority priority
When HSRP is configured on an interface, the router progresses through a series of states
before becoming active. This forces a router to listen for others in a group and see where itfits into the pecking order. The HSRP state sequence is Disabled, Init, Listen, Speak,
Standby, and, finally, Active.
Only the standby (second highest priority) router monitors the hello messages from the
active router. By default, hellos are sent every 3 seconds. If hellos are missed for the
duration of the holdtime timer (default 10 seconds, or 3 times the hello timer), the active
router is presumed down. The standby router is then clear to assume the active role. If other
routers are sitting in the Listen state, the next-highest priority router is allowed to become the
new standby router.