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which next hop will be used as the forwarding next hop for the generated route?

A generated route is used to create a route of last resort when BGP routes from the 10.0.0.0/23
block are present. Given the following output, which next hop will be used as the forwarding next
hop for the generated route?

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A.
172.16.0.2

B.
172.16.0.6

C.
172.16.0.10

D.
172.16.0.14

Explanation:

3 Comments on “which next hop will be used as the forwarding next hop for the generated route?

  1. kiyokaa says:

    Answer is not presented in this question

    1) best preference chosen first
    2) in a tie, lowest IP address – which is 0.0.0.0 in this question, but the generated route is only for the range of 10.0.0.0 – 10.0.1.255, so the default route doesnt go under the summary anyway.
    all other options have the same IP address.

    3) in a tie, smallest prefix length will bechosen – since 10.0.0.0/23 has the smallest prefix length, then it should be the contributing route for setting the next-hop for the generated route, which would be 172.16.0.8, but this answer doesn’t present in the options so none of the answers are valid for the question.

    see this link:
    https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/policy-edit-routing-options.html




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    1. kiyokaa says:

      My mistake, the quetsion says “last resort route” = 0.0.0.0/0, therefore answer C should be chosen as the generated route is a 0.0.0.0/0 which indeed included inside a default route of 0.0.0.0/0.
      set routing-options generate 0.0.0.0/0




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      1. kiyokaa says:

        gotta corerct myself again :[
        a generated route cannot be generated from an default route.

        I labbed it, and if you want to create a default generated route of 0.0.0.0/0, and a default route is already exists with a valid next-hop, then the generated route will ignore it and will use the next prefix which summarized under our generated route with his next-hop for the generated route as follow:
        1) lowest preference value prefix
        2) if tie, lowest IP address prefix
        3) if tie, smallest prefix length.

        therefore this the question we have 3 prefixes which aren’t a default route, they both have the same preference and the same IP address, so the prefix with the smalles prefix length should be chosen as the next-hop for the generated route, which is 10.0.0.0/23’s next-hop which dosn’t appear as an option.

        conclusion:
        the real and accurate answer for thsi question isn’t available, none of the answers are correct!




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