350-401 Exam - Question 513

B. is ONLY valid if the "other" router has preemption enabled. How can anybody tell? D. wrong E. wrong Correct answers A. since the local router has preemption enabled with a minimum 5 sec. delay it becomes the active router. C. Obviously the virtual IP is 10.1.1.1

Not b. You don’t know if other router will have preempt. Timers a default and vip is correct

I do not think A can be correct because the router would not be considered down until the 10 second hold time has elapsed and only then would the 5 second preempt start. A mentions time after a missed hello not after a down state. B+C are what I would pick.

A seems correct. Why? The Delay minimum quoted as 5 secs in the question means preempt delay. The preempt delay means that, when the interface gets up it will detect that there is already an hsrp neighbour active. Thus, that active router will continue forward traffic, and this router will wait for configured time until it takes over the role. If we don't wait, we will take over the active role immediate and that can be a problem if routing is not yet ready. Also, if the other router is not detected, this router will take the active role immediate, and do not wait the configured time, and starts forward traffic as soon as routing is ready. Source : https://community.cisco.com/t5/switching/hsrp-delay-minimum-amp-reload-question/td-p/3327186 C of course is right as seen from the output that the VIP is 10.1.1.1

HSRP uses two types of timers — hello and hold timers — to ensure redundancy among routers. The hello timer sends multicasts, or hello packets that broadcast status and priorities every three seconds. By default, if you don't tune in anything, the active and standby routers will say "hello" to each other once every three seconds. The hold timer tells the standby router when to take over. The standby router becomes active when it hasn't received a hello packet from the primary router in 10 seconds. So, worst case scenario, you've got 10 seconds before a standby router takes over and the timer settings can be lowered. A- Are wrong because Standby router only take over after 10 sec not 5 sec base on default hello timer and hold timer

Not A: hold timer is 10 seconds (not 5 sec)

the rest choices are false (deduction method in the mathematics)

The priority field is used to elect the active router and the standby router for the specific group. In the case of an equal priority, the router with the highest IP address for the respective group is elected as active. Furthermore, if there are more than two routers in the group, the second highest IP address determines the standby router and the other router/routers are in the listen state. https://www.cisco.com/c/en/us/support/docs/ip/hot-standby-router-protocol-hsrp/9281-3.html#q4

Only C) is valid right now. In order for B) to work, preemption needs to be enabled on the new device. We do not have that information about the new device. Preemption is not enabled by default in HSRP.

its deffinitely BC

BC is correct

Here is a LAB (eve-ng) verification of answer A: R3#show standby Ethernet0/0 - Group 2 (version 2) State is Standby 4 state changes, last state change 00:03:31 Virtual IP address is 10.1.1.1 Active virtual MAC address is 0000.0c9f.f002 Local virtual MAC address is 0000.0c9f.f002 (v2 default) Hello time 3 sec, hold time 10 sec Next hello sent in 2.512 secs Preemption enabled Active router is 10.1.1.2, priority 255 (expires in 9.120 sec) MAC address is aabb.cc00.7000 Standby router is local Priority 100 (default 100) Group name is "hsrp-Et0/0-2" (default)

Not enough information to deduce that B will be true. Preemption is required and that's not indicated.

B does seem to be the best 2nd answer but the "5 seconds later" is a problem because we don't know what the preempt settings are on the other routers. We can only assume all have preempt enabled with 5 second delay.

Its A and C

Confirmed in CML A is the answer. We do not have enough info for B to be accurate. I killed the linke from R1 to R2 and R2 took over even with priority of 100 over 255. Simply because preempt is enabled on R2 Its easy for everyone here to talk and link articles, but have you guys actually labbed this stuff to find out if it practically works? Too many book worms around here. HSRP_R1(config-if)#do show standby GigabitEthernet0/1 - Group 0 (version 2) State is Standby 12 state changes, last state change 00:00:41 Virtual IP address is 10.10.1.1 Active virtual MAC address is 0000.0c9f.f000 Local virtual MAC address is 0000.0c9f.f000 (v2 default) Hello time 3 sec, hold time 10 sec Next hello sent in 0.048 secs Preemption disabled Active router is 10.10.1.3, priority 100 (expires in 9.872 sec) MAC address is 5254.001e.efc3 Standby router is local Priority 255 (configured 255) Group name is "hsrp-Gi0/1-0" (default)

B and C are correct