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which statement is true?

— Exhibit —
[edit protocols ospf]
user@area-1-abr# show
area 0.0.0.1 {

nssa {
default-lsa {
default-metric 10;
metric-type 2;
type-7;
}
no-summaries;
}
interface so-0/1/1.0;
}
— Exhibit —
Click the Exhibit button.
Referring to the exhibit, which statement is true?

PrepAway - Latest Free Exam Questions & Answers

A.
The ABR will generate a Type 3 summary default route into the NSSA.

B.
The ASBR will generate a Type 7 default route into the NSSA.

C.
The type-7 parameter allows interoperability with newer versions of the Junos OS.

D.
The only LSA types allowed into the area are Type 1, Type 2, Type 3, and Type 7.

10 Comments on “which statement is true?

  1. steve q says:

    none of these answers are correct. The ABR will be the one to generate a default LSA, but it will be a Type 7. The ASBR generates type 7’s for the external prefixes when redistributed into OSPF, but will not generate a default route lsa.




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    1. JM says:

      You are correct.

      that is not worded correct.

      According to Juniper, it is the ABR that generates the type 7 def. route

      http://www.juniper.net/documentation/en_US/junos13.3/topics/topic-map/ospf-stub-and-not-so-stubby-areas.html

      user@host# set protocols ospf area 0.0.0.9 nssa

      On the ABR, enter OSPF configuration mode and specify the NSSA area 0.0.0.9 that you already created.
      [edit ]
      user@host# edit protocols ospf area 0.0.0.9 nssa

      On the ABR, inject a default route into the area.
      [edit protocols ospf area 0.0.0.9 nssa]
      user@host# set default-lsa default-metric 10

      (Optional) On the ABR, specify the external metric type for the default route.
      [edit protocols ospf area 0.0.0.9 nssa]
      user@host# set default-lsa metric-type 1

      (Optional) On the ABR, specify the flooding of Type 7 LSAs.
      [edit protocols ospf area 0.0.0.9 nssa]
      user@host# set default-lsa type-7

      On the ABR, restrict summary LSAs from entering the area.
      [edit protocols ospf area 0.0.0.9 nssa]
      user@host# set no-summaries

      If you are done configuring the devices, commit the configuration.
      [edit protocols ospf area 0.0.0.9 nssa]
      user@host# commit




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  2. koraa says:

    Answer should be A according to the route guide:

    ” ABR Injects a Default Route
    The ABR of the stub area can optionally inject a 0.0.0.0/0 default route into the stub area. Using the
    default-metric command accomplishes this task, which causes the ABR to generate a Type 3
    summary LSA advertising the 0.0.0.0/0 route with the associated metric attached.”




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    1. koraa says:

      Oh, and this link makes answer B valid (depending the JUNOS version?) https://www.juniper.net/documentation/en_US/junos14.1/topics/topic-map/ospf-stub-and-not-so-stubby-areas.html

      “type-7—(Optional) Floods Type 7 default LSAs into the NSSA if the no-summaries statement is configured. By default, when the no-summaries statement is configured, a Type 3 LSA is injected into NSSAs for Junos OS release 5.0 and later. To support backward compatibility with earlier Junos OS releases, include the type-7 statement.”




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  3. Rigpa says:

    B is the correct answer.

    LSA type 7 NSSA is only generated by an ASBR. The ABR that faces the backbone will convert those LSA type 7 in to LSA type 5 when it injects them in to the backbone. The only way that an ABR generates a type 7 LSA is if the type-7 statement is configured in conjunction with no-summaries, on this case, the default route (generated by the ABR) use to reach other networks beyond the NSSA area will be an LSA type 7.

    -“Meditation is the medicine of the mind”




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  4. Rigpa says:

    Taking back..

    None of the answer are correct, Steve q has a point.

    ABR will generate LSA type 7 as default route for the NSSA area due to configuration applied.

    ASBR generates LSA type 7 from external prefixes redistributed in to OSPF for NSSA area but no the default route as stated on the ansewer.

    D is not correct since LSA type 3 will not be present in the area due to the configuration applied on the ABR.

    -“Meditation is the medicine of the mind”




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  5. brice says:

    A is correct

    A. The ABR will generate a Type 3 summary default route into the NSSA.
    >> the default route generate by NSSA or Stub is Type 3.

    B. The ASBR will generate a Type 7 default route into the NSSA.
    >> same remark as previous

    C. The type-7 parameter allows interoperability with newer versions of the Junos OS.
    >> never heard about it

    D. The only LSA types allowed into the area are Type 1, Type 2, Type 3, and Type 7.
    >> there are no type 3 because of the no-summaries option




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  6. asd says:

    Basaically B and D could be potentially correct.

    On one hand, router generating externals (in this case, type-7’s) is defined as ASBR.
    On the other hand, NSSA no-summaries can have only type 1,2,3 and 7 LSA’s.
    Why also Type-3? Because:
    type-7—(Optional) Floods Type 7 default LSAs into the NSSA if the no-summaries statement is configured. By default, when the no-summaries statement is configured, a Type 3 LSA is injected into NSSAs for Junos OS release 5.0 and later. To support backward compatibility with earlier Junos OS releases, include the type-7 statement.

    Or maybe statement ‘allowed into the area’ means from outside.

    That’s a bad written question.




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