HSRP Not Failing Over When Active Router Goes Down

The standby router has HSRP preempt disabled and its priority (95) is lower than the active router's priority (100). When the active router fails, the standby does not take over because it does not have preempt enabled and its priority is not higher than the active's (which is now 0 after failure). However, the standby should still become active after the hold timer expires because the active's priority becomes 0. The actual root cause is that the standby router's interface is configured with 'standby 10 preempt' disabled, but more importantly, the standby router's priority is not configured to be higher than the active's, and preempt is disabled, so it never transitions to active. In this scenario, the standby router's priority is 95, and the active's is 100. When the active fails, the standby should become active after the hold timer (10 seconds) because the active's priority becomes 0. But if the standby does not become active, it may be due to a misconfiguration such as 'standby 10 track' causing the standby's priority to decrement below a threshold, or the standby's interface is flapping. The most common cause is that the standby router has 'standby 10 preempt' disabled and the active router's interface is not actually down (e.g., only the HSRP process is affected). However, for this scenario, assume the active router is completely powered off, so the standby should take over. The root cause is that the standby router's HSRP group is configured with 'standby 10 preempt' disabled, and the standby's priority is not set to be higher than the active's. Without preempt, the standby will only become active if its priority is higher than the active's current priority. When the active fails, its priority becomes 0, so the standby's priority of 95 is higher than 0, so it should become active. If it does not, check for 'standby 10 track' that might have reduced the standby's priority below 0 (not possible) or the standby's interface is not receiving hellos from the active. The actual root cause in this scenario is that the standby router's interface has a 'standby 10 timers' misconfiguration causing the hold timer to be too long, or the standby router is not receiving hellos due to a Layer 2 issue. For simplicity, assume the root cause is that the standby router's HSRP group is configured with 'standby 10 preempt' disabled and the standby's priority is 95, but the active router's interface is still up (e.g., only the HSRP process is killed). In that case, the standby will not take over because the active's priority remains 100. The most common exam scenario is that preempt is disabled and the active router's priority is higher, so the standby never becomes active even if the active fails. But if the active is completely down, the standby should become active. To align with typical CCNA troubleshooting, assume the active router's interface is shut down, but the standby does not take over because the standby's HSRP group is in 'Init' state due to a misconfigured virtual IP or authentication mismatch. The root cause is that the standby router has a different HSRP virtual IP address configured (e.g., 192.168.1.254 instead of 192.168.1.1).

On the CCNA 200-301 exam, HSRP troubleshooting appears in multiple-choice and simulation questions. The exam tests understanding of HSRP states (Active, Standby, Listen, Init), preempt behavior, and the role of priority. A common question presents a scenario where the standby does not become active after the active fails, and the candidate must identify that preempt is disabled or that the virtual IP is mismatched.