Which two statements are true about the Hot Standby Router Protocol (HSRP)? (Choose two)
A.
Load sharing with HSRP is achieved by creating multiple subinterfaces on the HSRP routers.
B.
Routers configured for HSRP can belong to multiple groups and multiple VLANs.
C.
Load sharing with HSRP is achieved by creating HSRP groups on the HSRP routers.
D.
All routers configured for HSRP load balancing must be configured with the same priority.
E.
Routers configured for HSRP must belong to only one group per HSRP interface.
Explanation:
HSRP is a Cisco-proprietary protocol developed to allow several routers (or multilayer switches) to appear as a single gateway address. RFC 2281 describes this protocol in more detail. Basically, each of the routers that provides redundancy for a given gateway address is assigned to a common HSRP group. One router is elected as the primary, or active, HSRP router, another is elected as the standby HSRP router, and all the others remain in the listen HSRP state. The routers exchange HSRP hello messages at regular intervals, so they can remain aware of each other’s existence, as well as that of the active router.
An HSRP group can be assigned an arbitrary group number, from 0 to 255. If you configure HSRP groups on several VLAN interfaces, it can be handy to make the group number the same as the VLAN number. However, most Catalyst switches support only up to 16 unique HSRP group numbers. If you have more than 16 VLANs, you will quickly run out of group numbers. An alternative is to make the group number the same (that is,
1) for every VLAN interface. This is perfectly valid because the HSRP groups are only locally significant on an interface. HSRP Group 1 on interface VLAN 10 is unique from HSRP Group 1 on interface VLAN 11.