OSPF Quiz

OSPF Quiz

Hi All
Sadly the quiz engine isn’t working as it should. However the questions below are still the same and should still help you if you want to dive deep into OSPF.
[mtouchquiz 1]

23 thoughts on “OSPF Quiz

      1. Dont confuse max metric with LSinfinity :
        RFC2328 > B. Architectural Constants
        LSInfinity
        The metric value indicating that the destination described by an
        LSA is unreachable. Used in summary-LSAs and AS-external-LSAs as
        an alternative to premature aging (see Section 14.1). It is
        defined to be the 24-bit binary value of all ones: 0xffffff.

  1. Great quiz! I got three wrong (same as Daniel and #7 as well. Was confused how I got 85%, but it seems you award partial credit for getting the right answer on your second try.
    Well done!

  2. Really nice interface, smooth, runs well. You going to do more?
    I got tripped up on the 65535 vs 16777342 one too, went with 16777342

    1. Hey Jeff,
      I probably will do another one, not sure when though. It’s hard to generate good questions. Actually it’s making sure I have the answers right is the hard part. No promises, but what would be a valuable space to cover, more OSPF or other topics?

  3. Q1 : There are no other routers on that network segment. RouterA has the DR role for that segment.
    The question is misleading. How come the RouterA has the DR role without any neighbor ? The DR role is negotiated during the adj process.
    Q4 : When does the ABR originate a type-4 summary on a Cisco router?
    I think that we can go deeper. Based on what is the ABR generating the LSA4 ?
    Dan

    1. Hi Dan,
      Thanks for the comment. I’m not sure that I’m misleading people about the DR role in Q1. You are correct that the DR is negotiated during the ADJ process, but what if there are no other speakers on that LAN segment when an OSPF interface starts-up.
      A router with an interface type of BCAST will correctly nominate itself as the DR if it hears from no other OSPF speakers before the expiry of the WAIT timer. Another speaker can then start up on the wire, learn of the existing DR (and move on the the subsequent steps of the adj formation process).
      I take your point on Q4. I guess I’m interested in the timing of the type-4 generation. I like your angle too.
      /John H

    1. Hey Rohan,
      Going great man. Hope Microsoft are looking after you. I wouldn’t be too worried about 75%, that’s quite a respectable score!.
      /John

    1. Hi Srinivasa,
      Thanks for the feedback. It was indeed theory based. My general philosophy is that you can handle most scenarios if you know the theory. To start, I wanted to create a quiz where the answers were provided in my previous theory-based posts.
      That said, I’m always happy to get feedback. Do you have any particular scenarios in mind? Which practical aspects of OSPF do you think are particularly tricky or worth covering? I can’t guarantee I’ll have the time to address your concerns, but always love suggestions from readers.

  4. you hit the nail with q: 4,5 and 7 – makes me think that I need to spend some more time on your website! Never knew about this site, I wonder how did I miss 🙂
    cheers John, hopefully your new role gives you some time to get back to this website? 🙂
    If you are looking for suggestions on future topics, I would love to see a similar series on the nitty-gritty of BGP and also some firewall/network security concepts! combined with use cases of the type of issues you have seen with designs of ospf/bgp and network security.
    take care,
    -muddassir

    1. Hi Muddassir,
      Thanks for taking the time to comment. The OSPF topics came from a period where I was testing the protocol for Amazon.
      I’m doing a fair bit of work on VPNs at the moment, so I might have some posts coming on those topics.
      Regards,
      John Harrington

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