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HSRP Questions

October 29th, 2018 Go to comments

Note: If you are not sure about HSRP, please read our HSRP tutorial.

Question 1

Explanation

First Hop Redundancy Protocol (FHRP) is a protocol that enables two or more devices to work together in a group, sharing a single IP address, the virtual IP address. One router is elected to handle all requests sent to the virtual IP address. With HSRP, this is the active router. An HSRP group has one active router and at least one standby router.

Question 2

Question 3

Explanation

Virtual Router Redundancy Protocol (VRRP) is one of the First Hop Redundancy Protocols that is supported by Cisco. Unlike HSRP and GLBP (which are Cisco proprietary protocols), VRRP is an industry standard protocol.

Question 4

Explanation

From this paragraph:

“A set of routers that run HSRP works in concert to present the illusion of a single default gateway router to the hosts on the LAN. This set of routers is known as an HSRP group or standby group. A single router that is elected from the group is responsible for the forwarding of the packets that hosts send to the virtual router. This router is known as the active router. Another router is elected as the standby router. If the active router fails, the standby assumes the packet forwarding duties. Although an arbitrary number of routers may run HSRP, only the active router forwards the packets that are sent to the virtual router IP address.

In order to minimize network traffic, only the active and the standby routers send periodic HSRP messages after the protocol has completed the election process. Additional routers in the HSRP group remain in the Listen state. If the active router fails, the standby router takes over as the active router. If the standby router fails or becomes the active router, another router is elected as the standby router.”

Reference: https://www.cisco.com/c/en/us/support/docs/ip/hot-standby-router-protocol-hsrp/10583-62.html#anc6

-> There is exactly one active router and one standby router in an HSRP group. Answer A is surely a correct but other answers are not correct. Answers C, D and E are wrong terminologies so they are surely not correct. Therefore answer B is a best choice left (although it is not totally correct).

Question 5

Explanation

HSRP consists of 6 states:

State Description
Initial This is the beginning state. It indicates HSRP is not running. It happens when the configuration changes or the interface is first turned on
Learn The router has not determined the virtual IP address and has not yet seen an authenticated hello message from the active router. In this state, the router still waits to hear from the active router.
Listen The router knows both IP and MAC address of the virtual router but it is not the active or standby router. For example, if there are 3 routers in HSRP group, the router which is not in active or standby state will remain in listen state.
Speak The router sends periodic HSRP hellos and participates in the election of the active or standby router.
Standby In this state, the router monitors hellos from the active router and it will take the active state when the current active router fails (no packets heard from active router)
Active The router forwards packets that are sent to the HSRP group. The router also sends periodic hello messages

Please notice that not all routers in a HSRP group go through all states above. In a HSRP group, only one router reaches active state and one router reaches standby state. Other routers will stop at listen state.

Question 6

Explanation

There are three First Hop Redundancy Protocols which are HSRP, VRRP and GLBP. HSRP and GLBP are Cisco proprietary protocols while VRRP is a standards-based protocol.

Question 7

Explanation

HSRP election is based on a priority value (0 to 255) that is configured on each router in the group. By default, the priority is 100. The router with the highest priority value (255 is highest) becomes the active router for the group. If all router priorities are equal or set to the default value, the router with the highest IP address on the HSRP interface becomes the active router. Below is an example of assigning HSRP priority of 200 to R1:

R1(config-if)# standby 1 priority 200

Question 8

Explanation

The “preempt” command enables the HSRP router with the highest priority to immediately become the active router. For example if we have a new router joining an HSRP of 1 and we want this router becomes the active router immediately (provided it had the highest HSRP priority) then we will need this additional command:

New_Router(config-if)#standby 1 preempt

Question 9

Explanation

Both HSRP version 1 & version 2 support preempt command -> Answer D is not correct.

In HSRP version 1, group numbers are restricted to the range from 0 to 255. HSRP version 2 expands the group number range from 0 to 4095 -> A is correct.

Question 10

Explanation

When all other routers in the group fail, the local router will not receive any HSRP Hello messages so it will become “active”. Notice that in this case the “preempt” command is not necessary. The “preempt” command is only useful when the local router receives a HSRP Hello message from the active HSRP router with a lower priority (then the local router will decide to take over the active role).

Question 11

Explanation

The virtual MAC address of HSRP version 1 is 0000.0C07.ACxx, where xx is the HSRP group number in hexadecimal based on the respective interface. For example, HSRP group 10 uses the HSRP virtual MAC address of 0000.0C07.AC0A. HSRP version 2 uses a virtual MAC address of 0000.0C9F.FXXX (XXX: HSRP group in hexadecimal)

For more information about HSRP operation, please read our HSRP tutorial.

Question 12

Explanation

With HSRP, two or more devices support a virtual router with a fictitious MAC address and unique IP address. There are two version of HSRP.

+ With HSRP version 1, the virtual router’s MAC address is 0000.0c07.ACxx , in which xx is the HSRP group. Therefore C is correct.
+ With HSRP version 2, the virtual MAC address is 0000.0C9F.Fxxx, in which xxx is the HSRP group.

Note: Another case is HSRP for IPv6, in which the MAC address range from 0005.73A0.0000 through 0005.73A0.0FFF.

(Good resource for HSRP: http://www.cisco.com/en/US/docs/switches/datacenter/sw/5_x/nx-os/unicast/configuration/guide/l3_hsrp.html)

Comments (28) Comments
  1. V
    March 15th, 2017

    what are 2 requirements of HSRP group?
    exactly one active router
    one or more standby router
    OR
    exactly one standby active router

    which is correct can someone please help?

  2. SJK
    March 18th, 2017

    The Correct answer is A and B as the standby must be of the secondary router

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    March 28th, 2017

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  4. KACS
    April 27th, 2017

    What are 2 requirements of HSRP group?
    Answers: 1-Exactly one active router. 2-One or more standby router.

  5. Muhammad Mohyuddin
    May 16th, 2017

    what are 2 requirements of HSRP group?

    A exactly one active router
    B exactly one standby active router

  6. ider
    May 21st, 2017

    Which configuration command can you apply to a router so that its local interface becomes active if all other
    routers in the group fail?
    A. Router(config)#standby 1 preempt
    B. No additional configuration is required
    C. Router(config)#standby 1 Priority 250
    D. Router(config)#standby 1 track Ethernet

  7. anonymous
    June 11th, 2017

    @ider i thnk the answer should be B. as others have failed, the router will automatically take over without additional config

  8. anonymous
    June 11th, 2017

    @ider B. as others have failed, the router will automatically take over without additional config

  9. Floyd
    June 28th, 2017
  10. Ihsan
    August 10th, 2017

    where are the question whose answers are discussed above.

  11. nickaro
    August 15th, 2017

    In Q.2 we have two correct answers, A and C. Anyone can show me the differences between them?

    If this is a CCNA real question, only one answer can be checked…

    Thank you in advance.

  12. Pls… Stop it and start helping
    September 10th, 2017

    For everyone who wants a valid full CCNA 200-125 –>DONT CLICK<— this link because it is just a bait… Its not the full version.. they want you to buy it!

    Fake link ( just a damn demo ): https://drive.google.com/open?id=0B5mAFqgydmCzc3BmR214LWFuTDg

  13. anon
    September 10th, 2017

    question 8.
    Can someone please fix the grammer on the question. It makes no sense.

  14. ali
    October 22nd, 2017

    9tut please
    what is the correct answer pleaaaaaaaaaaaaaaaaaaase
    Which value is used to determine the active router in an HSRP default configuration?

    A.Router loopback address
    B.Router IP address
    C.Router priority
    D.Router tracking number

  15. Avi
    November 5th, 2017

    @ali ans is c

  16. doka
    December 14th, 2017

    @ali
    Answer B
    HSRP DEFAULT configuration Priority=100 on all routers, then Router IP address

  17. HRR
    February 6th, 2018

    Which three statements about HSRP operation are true? (Choose three)
    A. The virtual IP address and virtual MAC address are active on the HSRP Master router. B. The HSRP default timers are a 3 second hello interval and a 10 second dead interval. C. HSRP supports only clear-text authentication. D. The HSRP virtual IP address must be on a different subnet than the routers‟ interfaces on the same LAN. E. The HSRP virtual IP address must be the same as one of the router‟s interface addresses on the LAN. F. HSRP supports up to 255 groups per interface, enabling an administrative form of load balancing

    A- HSRP use active router and standby router terms, Master router and backup router is for VRRP standard-based protocol.
    B- is correct
    C- is correct
    Authentication
    The HSRP authentication feature consists of a shared clear-text key contained within the HSRP packets. This feature prevents the lower priority router from learning the standby IP address and standby timer values from the higher priority router.

    To configure the HSRP authentication string, use the standby authentication string command.
    https://www.cisco.com/c/en/us/support/docs/ip/hot-standby-router-protocol-hsrp/9234-hsrpguidetoc.html#authentication
    D and F are incorrect
    F is correct (version 1 255 groups and version 2 4096 groups) although the correct way is supports up to 256 groups (0 to 255)

  18. Charice :)
    March 29th, 2018

    can someone explain how the answer for q12 worked out

    Thanks

  19. AB
    April 22nd, 2018

    @ Charice

    Q12 – Its self-explanatory.

    With HSRP version 1, the virtual router’s MAC address is 0000.0c07.ACxx , in which xx is the HSRP group. Therefore C is correct – 0000.0C07.AC15.
    With HSRP v1, the MAC address syntax is always – 0000.0c07.ACxx. The 15 after AC group is just a random number.

    Hope it helps

  20. Lily
    April 29th, 2018

    @AB

    Thanks it makes sense :)

  21. cthelite
    May 2nd, 2018

    @HRR… your answer is a little confusing… for clarification… the answer is A, B, and F

    C is NOT correct:

    From cisco.com – First Hop Redundancy Protocols Configuration Guide, Cisco IOS XE Release 3S
    Chapter: HSRP MD5 Authentication

    HSRP MD5 Authentication –
    Before the introduction of HSRP MD5 authentication, HSRP authenticated protocol packets with a simple plain text string. MD5 authentication provides greater security than the alternative plain text authentication scheme.

    HSRP has two authentication schemes:
    Plain text authentication
    MD5 authentication

    MD5 is also an option for authentication, along with a clear-text option… therefore C is not correct.

  22. Jorge
    June 2nd, 2018

    Hi! Does anybody know the answer to this question:

    Which value is used to determine the active router in an HSRP default configuration?

    A. Router loopback address
    B. Router IP address
    C. Router priority
    D. Router tracking number

  23. mostafa ahmed
    June 5th, 2018

    Hi

    ABOUT Q4 ..

    the answer should be A,D

    CAUSE ..
    ” only the active and the standby routers send periodic HSRP
    messages after the protocol has completed the election process ” ..

    So the Active and the standby routers are only the active at the same time .. so if there are another standby routers they will be in inactive status till the active standby or the active router down.

  24. Bisscay
    June 11th, 2018

    @ Jorge, at default configuration, all priorities are set to 100
    the highest loopback address assigned to each router will determine the active
    if a loopback address is absent, the highest IP address is then considered

  25. Bisscay
    June 18th, 2018

    further research has proven my initial choice wrong,
    at equal priorities,
    the next decider is the highest REAL ip address.
    Therefore the answer should be option B

  26. Mody
    July 8th, 2018

    About Q4 …
    i think in HSRP there is must be exactly one active router and exactly one standby router
    all the other routers will be called (listeners) …
    so i think the answers will be A , D
    i need a confirmation for that …
    anyone passed with 100 % can confirm it ??

  27. juba
    September 18th, 2018

    q9 a and b are true

  28. crispty
    October 7th, 2018

    Question 11
    A. The virtual IP address and virtual MAC address are active on the HSRP Master router.
    Can someone explain me this? what does means active on HSTP MARTER ROUTER?, it wants to say ACTIVE ROUTER?,

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