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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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Let's jump in with
our first question.

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If you enable area
0 authentication

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but do not provide a key
for the virtual link,

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what will happen on IOS XE?

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So one of our keys
here, of course,

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is that we are, in fact,
talking about IOS XE.

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Keep that in mind.

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And of course, the
question is, what

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happens if we don't provide a
key on the actual virtual link?

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So what are our choices here?

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Well, we have number one
says, the virtual link

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will come up using
default key 0.

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That actually sounds correct.

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Let's hold on to
that for a minute

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and look at the other answers.

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Number two says,
the virtual link

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will come up by
using default key 1.

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Now, if you remember, when
we were configuring this,

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we were using key 1.

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So there's not a default key 1.

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There's just the one we created.

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So that would make two an
incorrect answer, because there

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is no default key 1.

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Answer number three says that
the virtual link will come up

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without authentication.

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Now, if you remember, this
is actually what IOS XR did.

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But we're talking about IOS XE.

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So this would be
incorrect for IOS XE.

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Number four, the virtual
link will not come up.

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By the way, this is the
answer I would prefer.

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I would actually prefer that the
virtual link did not come up.

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Sadly, however, this
is not the case.

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The virtual link in
fact will come up.

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And as answer one says, it will
come up using a default key 0.

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So in this case, that makes
answer one the correct answer.

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Next question, if
you configure OSPF

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timers using the following
command, what will

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be the resulting Hello timer?

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ip ospf dead-interval
minimal hello-multiplier 4.

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So this is fairly
straightforward

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if we remember what
these things do.

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Minimal simply means
that it will be 1 second.

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But remember that
the minimal here is

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referring to the dead-interval.

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You then set the
Hello multiplier.

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And in this case,
we're setting it to 4.

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This simply means
that we're going

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to send four times Hellos,
because again, this

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is going with the Hellos,
per every dead interval.

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So if we're going to send
four Hellos in 1 second

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and 1 second, of course,
is 1,000 milliseconds,

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we divide this by 4.

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This is going to be
250 milliseconds.

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Therefore, our correct
answer is going

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to be three, 250 milliseconds.

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No need to go down the list
here since it's just math.

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Final question, which
of the following

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is provided using OSPF
MD5 authentication?

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Now, of course,
the big key to this

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is to remember that the MD5 is--

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well, it's providing
authentication.

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So let's go down our list.

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Does authentication
provide data integrity?

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That would generally
be something

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like a hash, something
like that would verify

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the data has not been changed.

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And the answer is
no, it does not.

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Does it provide LSA validation?

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Not directly.

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You could possibly
make an argument

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that two could be
correct just simply

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because I won't take an LSA
from a nonvalid neighbor.

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But it's certainly not
doing LSA validation itself.

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And we sort of just
gave away number three

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that what it does do
is neighbor validation.

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It makes sure that you will only
neighbor up with the routers

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that you intend to
neighbor up with.

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Does it give data privacy,
which would probably normally

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be referred to as encryption?

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And the answer is no, not in
OSPF using MD5 authentication.

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We do not get encryption
or data privacy.

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And nothing about this
gives us compression.

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So number five, LSA compression,
no, this just isn't something

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that we provide.

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So this means that our
answer for this question

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is number three.

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So that concludes this quiz.

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If you feel you were missing
any of the information needed

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to answer any of
these questions,

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I would encourage you
to go back and review

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the sources referenced on
the bottom of each question.

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Otherwise, congratulations
on completing Authentication,

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Virtual Links, and Optimization.

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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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