Which two statements are true about HSRP, VRRP, and GLBP? (Choose two)
A.
GLBP and VRRP allow for MD5 authentication, whereas HSRP does not.
B.
HSRP allows for multiple upstream active links being simultaneously used, whereas GLBP does not.
C.
GLBP allows for router load balancing of traffic from a network segment without the different host IP configurations required to achieve the same results with HSRP.
D.
Unlike HSRP and VRRP, GLBP allows automatic selection and simultaneous use of multiple available gateways.
E.
GLBP allows for router load balancing of traffic from a network segment by utilizing the creation of multiple standby groups.
Explanation:
1. GLBP
To provide a virtual router, multiple switches (routers) are assigned to a common GLBP group. Rather than having just one active router performing forwarding for the virtual router address, all routers in the group can participate and offer load balancing by forwarding a portion of the overall traffic.
2. VRRP
The Virtual Router Redundancy Protocol (VRRP) is a standards-based alternative to HSRP, defined in IETF standard RFC 2338. VRRP is so similar to HSRP that you need to learn only slightly different terminology and a couple of slight functional differences.
1. VRRP provides one redundant gateway address from a group of routers. The active router is called the master router, while all others are in the backup state. The master router is the one with the highest router priority in the VRRP group.
2. VRRP group numbers range from 0 to 255; router priorities range from 1 to 254 (254 is the highest; 100 is the default).
3. The virtual router MAC address is of the form 0000.5e00.01xx, where xx is a two-digit hex VRRP group number.
4. VRRP advertisements are sent at 1-second intervals. Backup routers can optionally learn the advertisement interval from the master router.
5. By default, all VRRP routers are configured to preempt the current master router, if their priorities are greater.
6. VRRP has no mechanism for tracking interfaces to allow more capable routers to take over the master role.
3. HSRP
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.