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[AUDIO LOGO]

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Congratulations on
completing another skill.

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Now, it's time for a review
in the form of a quiz.

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So let's go ahead and jump
in with our first question.

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How many types of hello
packets does IS-IS support?

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So sort of the key
here is we're actually

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looking at types of packets,
not just categories.

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If you remember, we said
that there's basically

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two categories--

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you have LAN and point-to-point.

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But under LAN, the
hellos are actually

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separated into level
one and level two,

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point-to-point just
uses one hello packet.

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So when we're talking
about types of packets,

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well, we have one type,
two types, and three types.

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So this would make three
our correct answer,

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there are three types
of hello packets

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essentially in two
different categories--

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LAN versus point-to-point.

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Next question.

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Once the Designated Intermediate
System or DIS is elected,

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how is the Backup Intermediate
System or the BIS elected?

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So we could theoretically go
through all of these answers.

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However, hopefully,
everybody remembers

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that unlike OSPF, which of
course does in fact use a PDR,

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there is no Backup in IS-IS.

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So there is no DIS.

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Therefore, the
correct answer here

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is it's not elected because
there is no such thing.

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So of course, the
fundamental principal

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to take away from this
question is there is no Backup.

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If the DIS fails, we
simply elect another one.

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Final question.

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On a broadcast network
type, how often

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will the DIS multicast
the CSNP to the LAN?

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So this is really just a
matter of memorization.

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And hopefully, you remembered
that every 10 seconds, the DIS

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multicast the CSNP to the other
devices on that LAN segment.

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So that concludes this quiz.

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Hopefully, you were able to
answer all of the questions.

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If not, I would encourage
you to go back and review

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the sources referenced
on each question

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so that you can gain
that missing knowledge.

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Otherwise, congratulations
on completing Explain IS-IS

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Operations.

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I hope this has been
informative for you.

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And I'd like to thank
you for viewing.

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