Question 839 - 350-401 discussion

Option B is the correct configuration to implement HSRP between two WAN routers with the given requirement.The configuration steps are as follows12:

Define the HSRP group number and the virtual IP address for the group using thestandby <group> ip command. In this case, the group number is 300 and the virtual IP address is 10.10.10.1:standby 300 ip 10.10.10.1.

Configure HSRP preemption and preemption delay using thestandby <group> preempt [delay [minimum] <seconds>]command. Preemption allows a router with higher priority to take over the active role from a router with lower priority. Preemption delay is the time that a router waits before taking over the active role in the HSRP group. In this case, the preemption delay is 100 seconds, which means that R1 will wait for 100 seconds before preempting R2 after R1 regains operational status:standby 300 preempt delay minimum 100.

Configure the HSRP priority for the router using thestandby <group> priority <value>command. The priority determines which router is the active router and which router is the standby router. The higher the priority, the more likely the router is to become the active router. In this case, R1 has a priority of 200 and R2 has a priority of 100, which means that R1 is the preferred active router and R2 is the standby router:standby 300 priority 200on R1 andstandby 300 priority 100on R2.

Option A is incorrect because it does not configure HSRP preemption and preemption delay, which are required by the question. Without preemption, R2 will remain the active router even if R1 has a higher priority and regains operational status.Without preemption delay, R1 will attempt to preempt R2 immediately, which may cause routing instability12.

Option C is incorrect because it configures HSRP preemption delay with thereloadkeyword, which means that the delay period applies only to the first interface-up event after the router has reloaded.This does not meet the requirement of the question, which states that the delay period should apply to any interface-up event after R1 fails and then regains operational status12.

Option D is incorrect because it configures HSRP preemption delay with thesynckeyword, which means that the delay period applies only to the first interface-up event after the router has reloaded, and only if such an event occurs within 360 seconds from reload.This does not meet the requirement of the question, which states that the delay period should apply to any interface-up event after R1 fails and then regains operational status, and without any time limit12.Reference:1:Configuring HSRP,2:HSRP Configuration Guide