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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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When you enable IS-IS
Prefix suppression,

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which of the following will
be advertised into IS-IS?

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So let's go ahead
and go down our list.

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Our first answer number
one is loopback interfaces.

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Now, that's actually something
that happens in OSPF,

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but that is not something
that happens in IS-IS.

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So loopback interfaces
is an incorrect answer.

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Number two is transit links.

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Well, honestly, this would
defeat the entire purpose

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of prefix suppression.

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So number two is
actually the opposite

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of what would be advertised.

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Number three is
passive interfaces.

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These, of course,
will be advertised.

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That's why the command
is advertise passive

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only because only passive
interfaces will get advertised.

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Of course, if answer
three correct,

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then answer four can't be
correct because they're

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mutually exclusive.

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So in this case,
our correct answer

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is number three,
passive interfaces.

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Next question.

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Which of the following
is the default behavior

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of IS-IS regarding
route propagation?

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So the first thing
to discuss here

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is that we are talking
about the default behavior,

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not what you as an
administrator can

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control because we know that
you can control route leaking.

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So what does it do by default?

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Number one says that it will
leak routes from Level 2

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to Level 1.

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That is not correct.

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By default, all Level
2 prefixes are blocked

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from going into Level 1.

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Remember that it
instead generates

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a default. Number two, it
will block routes from Level 2

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to Level 1.

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Well, that is what we just said.

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So yes, two is a correct answer.

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Number three, it will block
routes from Level 1 to Level 2.

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This is actually not correct.

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In fact, it will
actually leak them.

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So at the same time that we mark
three as an incorrect answer,

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it does mean that five becomes
our correct answer because it's

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saying that it will leak the
routes from Level 1 to Level 2.

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Now, four and six here,
if we look at them,

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are sort of, again, exclusive
if these other answers

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were correct.

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It will leak all
routes between levels.

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Well, no, we just established
that's not the case.

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And number six, it will block
all routes between levels.

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Again, we just established
that that's not correct either.

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So the correct answer
to the default behavior

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is it will block routes
from Level 2 to Level 1,

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and it will leak routes
from Level 1 to Level 2.

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So two and five are
the correct answers.

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Final question.

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What two elements can be
authenticated in IS-IS?

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So this is simply a matter
of remembering the two things

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that we can authenticate in
IS-IS are the IS-IS hellos

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and the LSPs or the exchanging
of the database itself.

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Once again, we can use
either plaintext or MD5

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for either one of these.

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They can use the same key
chain or different key chains.

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So we have some
flexibility here.

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And of course, we
can enable just one

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of these or the other one
or both or, well, neither,

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although that's not
generally recommended.

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But these are the two things
that can be authenticated.

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So that concludes this quiz.

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If you feel that you are missing
any of the elements needed

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to answer these
questions, I would

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encourage you to go back
and review the reference

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sources on each question.

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Otherwise, congratulations on
completing Implementing IS-IS

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Advanced Features.

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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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