You are troubleshooting a problem with two routers configured in a HSRP group. You intended to configure the routers so that Router A and Router B would each track their respective Fa0/1 interfaces and decrement their priorities for several VLAN groups if the tracked interface went down. However, you find that Router A is not taking over as the active device for the HSRP group on VLAN 101 when the Fa0/1 interface on Router B fails.
Which command would NOT be useful for discovering the problem?
A. show running-configuration
B. show vlans
C. show standby brief
D. show standby
Correct Answer: B
Explanation:
The show vlans command would NOT be useful for discovering the problem. When troubleshooting a problem with Hot Standby Router Protocol (HSRP), the show vlans command will yield no useful information.
All three of the remaining commands will be useful in discovering information. Each is shown below with an example of its application to troubleshooting. Example A: show running-configuration
Router B is not taking over as the active device for VLAN 101’s HSRP group when the Fa0/1 interface on Router A fails. Below is a partial output of show run for both routers with the output focused on the section concerning VLAN 101’s configuration on each.
The above output displays the source of the problem. Router A has a decrement value of 5 configured for Fa0/1, as shown on the last line of the output after the specification of Fastethernet 0/1. This means that when its Fa0/1 interface goes down, Router A will subtract 5 from its priority for the VLAN 101 group, lowering it to
175. This is still higher than the priority of Router B, which is 170. Therefore, the solution is to change the decrement value for Router A to at least 11. When the interface goes down, Router A’s priority will be decremented to 169, allowing Router B to take the role as active for the HSRP group in VLAN 101.
Example B: show standby brief
Router C is not taking over as the active device for VLAN 102’s HSRP group when the Fa0/1 interface on Router D fails. Below is a partial output of show standby brief for both routers C and D, with the output focused on the section concerning VLAN 102’s configuration on each.