You have configured switches A and B in a network. The gigabitethernet0/1 interface of switch A has HSRP enabled on it for VLAN 30. Switch A has a priority of 240 and switch B has a priority of 200 for the HSRP group. You want to ensure that if the gigabitethernet0/1 interface of switch A goes down, then switch B becomes the active HSRP switch for the VLANs. You have executed the standby preempt command on switch B.

Which of the following commands should be used on switch A to achieve the desired results?

A. standby 30 track gigabitethernet0/1
B. standby 30 track gigabitethernet0/1 10
C. standby 30 track gigabitethernet0/1 30

D. standby 30 track gigabitethernet0/1 45

Explanation:

The standby 30 track gigabitethernet0/1 45 command should be used on switch A so that switch B becomes the active switch in case the gigabitethernet0/1 interface of switch A fails. The standby track command allows you to track an HSRP-enabled interface on a switch. When the tracked interface fails or goes down, the priority of the active switch in the given HSRP group is decremented. The default decrement value for the tracked interface is 10, which means that the priority value of the HSRP switch is decremented by 10. Additionally, if the standby preempt command is used on another switch, then that switch becomes the active switch for the group if it has a higher priority.

In this case, the standby 30 track gigabitethernet0/1 45 command decrements the HSRP priority of switch A for group 30 (VLAN 30) by 45 when gigabitethernet0/1 goes down. As a result, the priority of switch A is reduced to 195, which is less than the priority of switch B. Therefore, switch B now has the highest priority and hence becomes the active switch for the group.

The other options are incorrect, as they do not reduce the priority of switch A to an extent that the priority of switch B is higher.

Objective:
Infrastructure Services
Sub-Objective:
Configure and verify first-hop redundancy protocols

References:
Cisco > Home > Support > Technology Support > IP > IP Application Services > Design > Design Technotes > How to Use the standby preempt and standby track Commands
Cisco Press > Articles > Cisco Certification > CCNP > High Availability Commands for CCNP BCMSN
Cisco > Cisco IOS IP Application Services Configuration Guide, Release 12.4 > Part 1: First Hop Redundancy Protocols > Configuring HSRP