[AUDIO LOGO]
Congratulations on completing another skill.
Now, it's time for a review in the form of a quiz.
As we go through these questions,
be sure to pause the video after each question to give yourself
the opportunity to answer the question yourself
before we then go over the answer.
That said, let's jump in with our first question.
What is the reverse path forwarding check?
So let's start just by going down through our answers
and seeing which ones sound good.
So number one says that we're going
to check the multicast table to make sure that the source is
still available.
That doesn't really sound correct--
the multicast table would really have
no way of knowing if the source is still available.
So let's look at answer two--
forwarding traffic along the unicast path to the source.
Well, we are sort of going to look at the unicast path
to the source, but we're not going to be forwarding traffic.
So let's go ahead and move on to three.
Using the unicast routing table to verify
the path to the source.
Well, we are going to use the unicast routing table.
That's correct.
And we are sort of doing this as a verification
to make sure that we're using the correct path if we
were going to try to send traffic back
towards the source.
So that actually sounds pretty good,
but let's check answer four.
Checking the path to the receiver to ensure it's
reachable.
Well, this is reverse path forwarding,
so it's not going to have anything to do with the path
to the receiver.
So four is clearly going to be incorrect.
So going back over our answers, I
would say that three is our best sounding answer.
That would make one and two incorrect as well.
So I would say that our correct answer for this question
is number three--
using the unicast routing table to verify
the path to the source.
Next, we have a fill-in-the-blank question--
what is a PIM sparse mode register message?
So again, as a fill in the blank,
as long as we have something similar to this answer,
we would consider it correct.
The original multicast frame is encapsulated into unicast
and sent or forwarded to the Rendezvous Point or the RP.
That's all a PIM register message is.
It's the original multicast frame sent through unicast
to the RP who then, remember, makes
an S, G entry so that we can then build a proper multicast
tree towards the source.
Final question, we have another fill in the blank--
what is the general principle of PIM dense mode?
So we could say that the general principle is to flood.
So when multicast traffic is received,
we're going to flood it out all PIM-enabled interfaces,
except, of course, the interface that it arrived on.
We wouldn't want to send it back out the same way
it came, of course.
But other than that, we default to flooding the traffic out all
of our PIM-enabled interfaces.
So that concludes this quiz.
If you feel that you are missing any of the information
to answer these questions, I would
encourage you to go back and review the sources referenced
on each question.
Otherwise, congratulations on completing discovering
multicast routing.
I hope this has been informative for you,
and I'd like to thank you for viewing.