Home > HSRP & VRRP Questions

HSRP & VRRP Questions

March 16th, 2020 in ENCOR 350-401 Go to comments

Question 1

Explanation

When you change the HSRP version, Cisco NX-OS reinitializes the group because it now has a new virtual MAC address. HSRP version 1 uses the MAC address range 0000.0C07.ACxx while HSRP version 2 uses the MAC address range 0000.0C9F.F0xx.

HSRP supports interface tracking which allows to specify another interface on the router for the HSRP process to monitor in order to alter the HSRP priority for a given group.

Question 2

Explanation

If you change the version for existing groups, Cisco NX-OS reinitializes HSRP for those groups because the virtual MAC address changes.

Reference: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus3548/sw/unicast/503_A1_1/l3_nx-os/l3_hsrp.html

Question 3

Question 4

Explanation

The main disadvantage of HSRP and VRRP is that only one gateway is elected to be the active gateway and used to forward traffic whilst the rest are unused until the active one fails. Gateway Load Balancing Protocol (GLBP) is a Cisco proprietary protocol and performs the similar function to HSRP and VRRP but it supports load balancing among members in a GLBP group.

Note: Although GLBP is not a topic for this exam but not sure why we still have this question!

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

A VRRP router receiving a packet with the TTL not equal to 255 must discard the packet (only one possible hop) -> B is correct.

Currently there are three VRRP versions which are versions 1, 2 and 3 -> E is correct.

VRRP uses multicast address 224.0.0.18 and supports plaintext or MD5 authentication.

Question 6

Comments
  1. thatonedude
    March 25th, 2020

    Question 2

    Which behavior can be expected when the HSRP versions is changed from 1 to 2?
    A. Each HSRP group reinitializes because the virtual MAC address has changed
    B. No changes occur because version 1 and 2 use the same virtual MAC OUI
    C. Each HSRP group reinitializes because the multicast address has changed
    D. No changes occur because the standby router is upgraded before the active router

    Answer: C

    Explanation

    When you change the HSRP version, Cisco NX-OS reinitializes the group because it now has a new virtual MAC address. HSRP version 1 uses the MAC address range 0000.0C07.ACxx while HSRP version 2 uses the MAC address range address range 0000.0C9F.F0xx.

    Shouldn’t the answer be “A” as the MAC is changing?

  2. Gentao
    April 3rd, 2020

    @that one dude i would agree the answer might be A

  3. nico
    April 6th, 2020

    224.0.0.2
    HSRP version 1 uses the multicast address 224.0. 0.2. HSRP version 2 uses multicast address 224.0. 0.102 for its communication.Sep

  4. Gentao
    April 6th, 2020

    Question answer should be A

    When you change the HSRP version, Cisco NX-OS reinitializes the group because it now has a new
    virtual MAC address.

    https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus3548/sw/unicast/503_A1_1/l3_nx-os/l3_hsrp.pdf

  5. Gre47
    May 19th, 2020

    Question 2 is 100% A. The Mac address changes when you change versions:

    “When the HSRP version is changed, each group will reinitialize because it now has a new virtual MAC address.”

    source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipapp_fhrp/configuration/15-mt/fhp-15-mt-book/fhp-hsrp-v2.html

  6. Nhardz
    June 3rd, 2020

    @Digitaltut,

    Q6 is not added in the composite i believe

  7. alex
    June 17th, 2020

    Question 6.
    VRRP Limitations
    The switch supports either HSRP or VRRP, but not both. The switch cannot join a stack that has both HSRP and VRRP configured.
    The VRRP implementation on the switch does not support the MIB specified in RFC 2787.
    The VRRP implementation on the switch supports only text -based authentication.
    The switch supports VRRP only for IPv4.

  8. ss
    July 11th, 2020

    Which statement about VRRP is true?
    A. It supports load balancing
    B. It can be configured with HSRP on a switch or switch stack
    C. It supports IPv4 and IPv6
    D. It supports encrypted authentication
    Answer is D
    ?
    vrrp group authentication md5 key-string [0 | 7] key-string [timeout seconds]
    Specifying 7 means the key will be encrypted. The key-string authentication key will automatically be encrypted if the service password-encryption global configuration command is enabled.
    anyone can confirm ?
    VRRP Limitations
    The switch supports either HSRP or VRRP, but not both. The switch cannot join a stack that has both HSRP and VRRP configured.
    The VRRP implementation on the switch does not support the MIB specified in RFC 2787.
    The VRRP implementation on the switch supports only text -based authentication.
    The switch supports VRRP only for IPv4.
    what would be the correct answer ?

  1. No trackbacks yet.