[AUDIO LOGO]
Congratulations on completing another skill.
Now it's time for a review in the form of a quiz.
Let's jump in with our first question.
Type 1 external lSAs increase the metric on the LSA
to account for internal costs.
True or false?
So for this question, we have to look at the wording
very carefully because Type 1 external LSAs do
account for internal costs.
That part is all correct.
The part that's a problem is where
it says that it increases the metric on the LSA.
This is the part that's not true.
The LSA is kept the same through the entire network.
What happens is the receiving device
then adds the metric to the cost to the advertising router,
and those are added together not in the LSA
but in the routing table.
Therefore, that makes this overall answer false
because we're not keeping the information in the LSA,
it's being calculated and then put into the routing table.
Next question, if you change auto-cost reference-bandwidth
to 10,000.
What would be the cost of a gigabit ethernet interface?
So what we need to remember for this question is
the auto-cost reference-bandwidth
is in megabits per second.
So essentially what that means is that this would
be 10,000 megabits per second.
And of course, gigabit is 1,000 megabits per second,
therefore number three would be our correct answer.
It would be a cost of 10.
Final question, which method of route selection
does IOS XR use for its Type 5 versus Type 7 LSAs?
So what we're really talking about here is with the Type 5s
these would be our E1s and E2s.
With the Type 7s, these would be the N1s and the N2s.
So what this question is really asking
is on IOS XR which RFC do we use when
determining if we prefer ease over ends or ends over ease?
Now we can start off by very quickly eliminating
RFC 2101 that has nothing to do with NSSA
neither does RFC 7711.
I don't even know what those two are.
They're just made up answers.
Now the two RFCs that are related to external versus NSSA
are RFC 1587 and 3101.
Remember the 1587 says to prefer E over N.
And 3101, which is the newer method,
says to prefer N over E.
So the question becomes, as of right now,
which of these methods is used by IOS XR.
And unfortunately the answer is RFC 1587.
I say unfortunately because it is the older method.
However, keep in mind that NSSAs or Not-So-Stubby Areas are not
necessarily the focus of iOS XR.
That would of course, make answer three here
an incorrect answer as well.
That's not supported on IOS XR, at least not right now.
So that leaves our correct answer as number two, RFC 1587.
So that concludes this quiz.
If you find that you are missing any of the information
here to answer these questions, I
would encourage you to go back and review the reference
sources on each question.
Otherwise, congratulations on completing OSPF path selection.
I hope this has been informative for you,
and I'd like to thank you for viewing.