CCNA 200-301 Practice Exam: The Spanning-Tree Protocol

With my new (and free!) STP Fundamentals course launching the week of March 15 on Udemy and GNS3 Academy, today’s free CCNA Bulldog Practice Exams are going to focus on – what else?  – the Spanning-Tree Protocol!  Let’s jump right in — and be sure to check back here and on my Twitter account @ccie12933 for the opportunity to join that free course (and I’ll throw in a free STP Study Guide!)

Question 1:

We’ll start with the truly fundamental fundamentals:  What exactly does STP work to prevent?

A.   Routing loops

B.   Switching loops

C.   Split Horizon

D.   Route Poisoning

E.  Physical loops


Question 2:  

What devices in a Cisco switching network originate Configuration BPDUs?

A.   Only the root switches.

B.   Only the non-root switches.

C.   Both the root and non-root switches; in short, every switch in your network originates these.

D.   Neither root nor non-root switches actually originate Config BPDUs.


Question 3: 

When it comes to a root bridge election, which BID wins?

A.  The lowest.

B.  The highest.


Question 4: 

What STP state is described here?  “The port cannot yet forward frames, but it can learn MAC addresses dynamically.”

A.   Listening

B.   Learning

C.   Blocking

D.   Forwarding

E.   Disabled


Question 5:

Which of these STP timers has a default setting of 20 seconds?

A.     MaxAge

B.     Forward Delay

C.     Hello Time

D.    All of these are set to 20 seconds by default.

And now.. the answers!

Answer 1:  B.   STP has one job — prevent switching loops.    STP has nothing to do with routing loop prevention.

Answer 2:  A.   The root switch originates Configuration BPDUs while the non-roots forward those same BPDUs.  This doesn’t sound like a big difference, but this allows the Config BPDUs to be originated with a root path cost of zero and to have that value accumulate as they’re forwarded throughout the network.    (To see this in action, join my CCNA STP Video Boot Camp next week!)

Answer 3:   B.    On eBay, the highest BID wins.   In root bridge elections, the lowest BID wins.

Answer 4:   B.  The name is the recipe, as this describes the STP Learning state perfectly.

Answer 5:   A.   MaxAge has a default setting of 20 seconds.   Forward Delay is set to 15 seconds by default, and Hello Time’s default is 2 seconds.

Thanks for taking this CCNA Bulldog Practice Exam, and for making me part of your success story.   See you on Twitter and YouTube!

Chris Bryant on Twitter

Chris Bryant’s CCNA YouTube Channel