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HSRP Hotspot

November 15th, 2018 in SWITCH 300-115 Go to comments

Question

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For your information, the “show running-config” commands are posted below for your reference but please notice in the exam you have to issue this command to get the output:

DSW1#show running-config

interface Vlan101
 ip address 192.168.101.1 255.255.255.0
 standby 1 ip 192.168.101.254
 standby 1 priority 200
 standby 1 track GigabitEthernet1/0/1 55
!
interface Vlan102
 ip address 192.168.102.1 255.255.255.0
 standby 2 ip 192.168.102.254
 standby 2 priority 200
 standby 2 preempt
 standby 2 track GigabitEthernet1/0/1 5
!
interface Vlan103
 ip address 192.168.103.1 255.255.255.0
 standby 3 ip 192.168.103.254
 standby 3 priority 200
 standby 3 preempt
 standby 3 track GigabitEthernet1/0/1
!
interface Vlan104
 ip address 192.168.104.1 255.255.255.0
 standby 4 ip 192.168.104.254
 standby 4 priority 150
 standby 4 preempt
 standby 4 track GigabitEthernet1/0/1 1
!
interface Vlan105
 ip address 192.168.105.1 255.255.255.0
 standby 5 ip 192.168.105.254
 standby 5 priority 150
 standby 5 preempt
 standby 5 track GigabitEthernet1/0/1 55
DSW2#show running-config

interface Vlan101
 ip address 192.168.101.2 255.255.255.0
 standby 1 ip 192.168.101.254
 standby 1 priority 150
 standby 1 preempt
 standby 1 track GigabitEthernet1/0/1
!
interface Vlan102
 ip address 192.168.102.2 255.255.255.0
 standby 2 ip 192.168.102.254
 standby 2 priority 190
 standby 2 preempt
 standby 2 track GigabitEthernet1/0/1
!
interface Vlan103
 ip address 192.168.103.2 255.255.255.0
 standby 3 ip 192.168.103.254
 standby 3 priority 190
 standby 3 preempt
 standby 3 track GigabitEthernet1/0/1 50
!
interface Vlan104
 ip address 192.168.104.2 255.255.255.0
 standby 4 ip 192.168.104.254
 standby 4 priority 200
 standby 4 preempt
 standby 4 track GigabitEthernet1/0/1 55
!
interface Vlan105
 ip address 192.168.105.2 255.255.255.0
 standby 5 ip 192.168.105.254
 standby 5 preempt
 standby 5 track GigabitEthernet1/0/1

Question 1

Explanation

The question clearly stated that there was an issue with the decrement value in VLAN 102 so we should check VLAN 102 on both DSW1 and DSW2 switches first. Click on the PC Console1 and PC Console2 to access these switches then use the “show running-config” command on both switches

DSW1>enable
DSW1#show running-config

DSW2>enable
DSW2#show running-config

HSRP_show_run

As shown in the outputs, the DSW1’s priority is 200 and is higher than that of DSW2 so DSW1 becomes active switch for the group. Notice that the interface Gig1/0/1 on DSW1 is being tracked so when this interface goes down, HSRP automatically reduces the router’s priority by a configurable amount, in this case 5. Therefore the priority of DSW1 goes down from 200 to 195. But this value is still higher than that of DSW2 (190) so DSW1 remains the active switch for the group. To make DSW2 takes over this role, we have to configure DSW1’s decrement value with a value equal or greater than 11 so that its result is smaller than that of DSW2 (200 – 11 < 190). Therefore C is the correct answer.

Question 2

Explanation

Continue to check VLAN 101 on both switches…

HSRP_show_run_2.jpg

We learned that DSW1 doesn’t have the “standby 1 preempt” command so it can’t take over the active role again even if its priority is the highest. So we need to enable this command on VLAN 101 of DSW1.

Question 3

Explanation:

HSRP_vlan103

The reason DSW2 has not become the active switch for Vlan103 is because the priority value of DSW1 is higher than that of DSW2. In order to make DSW2 become the active switch, we need to increase DSW2’s priority (to higher than 200) or decrease DSW1’s priority (to lower than 190) -> B and C are correct.

But there is another requirement from this question that “A failure on gig1/0/1 on primary device should cause the primary device to release its status as the primary device, unless GigabitEthernet 1/0/1 on backup device has also failed”. This requirement makes answer B incorrect. For example, we choose to decrease the priority value on DSW1 to 160 (according to answer B) then DSW2 will become active switch (that is good). When Gi1/0/1 on DSW2 goes down, the priority of DSW2 will be 190 – 50 = 140 < 160 -> DSW1 will become new active switch (it is good, too). But when Gi1/0/1 on DSW1 also goes down, the priority of DSW1 will be 160 – 10 = 150 and it is still greater than 140 of DSW2 -> DSW2 cannot retake the active role as the requirement of this question.

Question 4

Explanation

Below is the output of VLAN 105:

HSRP_vlan105.jpg

If G1/0/1 on DSW1 is shutdown, its priority will decrease 55 so, its value will be 150 – 55 = 95

Question 5

Explanation

Below is the output of VLAN 105 of DSW2:

HSRP_vlan105_DSW2.jpg

We don’t see the priority of DSW2 so it is using the default value (100).

Question 6

Explanation

HSRP_vlan104

The question asks us how to keep the active role of DSW2. From the outputs, we learned that if both interfaces G1/0/1 of DSW1 and DSW2 are shutdown, the priority of DSW1 will be 150 – 1 = 149 and that of DSW2 will be 200 – 55 = 145 -> DSW1 will become the active switch.

The main point here is that we have to configure so in such a way that when both interfaces G1/0/1 of DSW1 and DSW2 are shutdown, the priority of DSW2 is still greater than that of DSW1. Therefore the priority value of DSW1 should be smaller than 145, or we have to configure the decrement value of DSW1 to a value greater than 6 ( 6 = 150 – 144) -> C is the correct answer.

Notice: To keep the active role of DSW2, we can disable “preempt” on DSW1 (answer A) so that it will not take over the active role when DSW2 is downed but it also means that VLAN 104 will not have active switch -> VLAN104 will fail.

Comments
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  1. Anonymous
    January 16th, 2019

    May I know that for Q1, why the answer is C but not A?

  2. Silas
    January 23rd, 2019

    for question 1, why isn’t “greater than 190 but less than 200” not a valid answer?

    If the priority for group 102 is set to 200, and it drops 199, router B will take over with a priority of 190.

    what am I missing here?

  3. sj28
    February 25th, 2019

    11 to 18 is the decrement range values we can use in order for dsw1’s priority be lower than dsw2 when the interface went down..
    5 to 15 is range values as well..not like instead of 5, use 15..

  4. Daniel
    March 7th, 2019

    Just pass SW 300-115 yesterday.
    No D&D, less than 4 or 5 new questions. Don’t remember clearly.
    Most of my questions from Dumps TestKing, Labs from certprepare: LACP & HSRP
    Great, thanks certprepare. Don’t worry mates if you understand every concepts.
    In case you need dumps, email me at: ballking242 @ gmail dot com

  5. supportdonkey
    April 4th, 2019

    Daniel is fake…This guy wants $

  6. Delarius
    September 2nd, 2019

    Is this HSRP hotspot like another lab in the exam ? is still showing or not anymore so I can focus on the other labs ???

  7. Bond007
    September 13th, 2019

    i have completed preparation for CCNP 300-115 from cisco official book. Now seeking for LABs, Please mates just tell which LABs i must prepare to clear the exam, and also tell is there a scenario question in 300-115? like a already configured LAB will be there and i have to answer the Questions. Thanks in Advance.

  8. xela
    October 15th, 2019

    Q3 please , someone that explicate it.

    Question 3
    DSW2 has not become the active device for Vlan103’s HSRP group even though all interfaces are active. As related to Vlan103’s HSRP group. What can be done to make the group function properly?

    A. On DSW1, disable preempt
    B. On DSW1, decrease the priority value to a value less than 190 and greater than 150
    C. On DSW2, increase the priority value to a value greater 200 and less than 250
    D. On DSW2, increase the decrement value in the track command to a value greater than 10 and less than 50.

    Answer: C

    if priority dsw2 = 230 for example never are active if down, A failure on gig1/0/1 on primary device dsw1 priority = 200-10 = 190 vs dsw2 = 230; DSW2 is Active but if dow also gig1/0/1 in dsw2 =
    dsw1=200-10 = 190
    dsw2=230 -50 = 180 , then dsw2 not are Active…
    not see solution correct for this escenary.

  9. DT
    October 28th, 2019

    Any report of this section being on the exam lately?

  10. Abdsamad
    November 10th, 2019

    Q3: The answer “On DSW2, increase the priority value to a value greater 200 and less than 250” is also incorrect :
    Let’s make DSW2 priority : 201 and DSW1 : 200 (don’t change) :
    So, when Gi1/0/1 on DSW2 and DSW1 goes down, the priority of DSW2 will be 201 – 50 = 151 DSW1 will still active switch.
    -> DSW2 cannot retake the active role as the requirement of this question.

  11. Abdsamad
    November 10th, 2019

    So, when Gi1/0/1 on DSW2 and DSW1 goes down, the priority of DSW2 will be
    201 – 50 = 151 < 200 – 10 = 190. So DSW1 will still active switch.

  12. Sol
    November 18th, 2019

    Shouldn’t we take gig1/0/2 into account? I assume that those links are trunk as well, in that case, disabling gig1/0/1 on both switches and disabling preemption on DSW1 still meets the requirements. (when both gig1/0/1 fails primary gw devices should retain its role) Because they have a redundant link (gig1/0/2).

  13. Epyon
    December 8th, 2019

    Question 3 – i think that correct one is B

    DSW1 has priority of 200 and default decrements of 10
    DSW2 has priority of 190 and decrements by 50

    As it is, DSW2 never becomes priority, cause at best it will have the same priority as DSW1 so preempt won’t work.

    Solution: Decrease priority of DSW1 to anything between 151-189 = put’s DSW2 as active, DSW1 as standby for V103, if DSW2 G1/0/1 goes down, it lowers it’s priority by 50 = 140
    140 is lower than 151-189 thus DSW1 becomes active. If DSW2 G1/0/1 goes up again, DSW2 priority rises by 50 to it’s org 190, and is higher than DSW1 151-189 so preempt works and put’s DSW2 as active and DSW1 as standby.

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