cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Announcements
Join Customer Connection to register!
624
Views
5
Helpful
5
Replies
bastien1
Beginner

STP question on the ICND2 book, wrong answer ?

Hello everyone,

I'm currently studying for the ICND2 and I'm having trouble understanding the answers (which are officially a & d) of this question (see the attached picture).

 

I agree with the "d" answer which is "This switch uses RSTP" but I don't agree with the "a" one stating "The root switch’s MAC address is 1833.9d7b.0e80 and the local switch is the root."

 

The output of the "show spanning-tree vlan 5" do not show any sentence saying "The bridge is the root" and there is no bridge ID in this output so we don't know what is the MAC address of this switch ...

 

Is this an error ?


Regards

 

 

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
Peter Paluch
Hall of Fame Cisco Employee

Hi Bastien,

You are absolutely right - there are fewer correct answers in that question than requested.

(a) is not correct because the SW1 is not the root switch. Exactly as you wrote, the "This bridge is the root" line is missing, and in addition, the outputs shows you the root port as Gi0/1. A root switch would not have any root port.

(b) is not correct because from the given output that only shows information about the root switch, you cannot determine the MAC address of SW1. If this was a realistic scenario, we can actually say that SW1 cannot have the same MAC address as the root switch - it would mean that two switches have the same MAC address.

(c) is not correct because the switch clearly says it runs RSTP.

(d) is obviously correct.

What I suggest doing is visiting the Cisco Press website, locating the particular book, and checking the published errata - perhaps this one is already known and recorded. If not, please report it so that it gets corrected in the next reprint.

Best regards,
Peter

View solution in original post

5 REPLIES 5
Peter Paluch
Hall of Fame Cisco Employee

Hi Bastien,

You are absolutely right - there are fewer correct answers in that question than requested.

(a) is not correct because the SW1 is not the root switch. Exactly as you wrote, the "This bridge is the root" line is missing, and in addition, the outputs shows you the root port as Gi0/1. A root switch would not have any root port.

(b) is not correct because from the given output that only shows information about the root switch, you cannot determine the MAC address of SW1. If this was a realistic scenario, we can actually say that SW1 cannot have the same MAC address as the root switch - it would mean that two switches have the same MAC address.

(c) is not correct because the switch clearly says it runs RSTP.

(d) is obviously correct.

What I suggest doing is visiting the Cisco Press website, locating the particular book, and checking the published errata - perhaps this one is already known and recorded. If not, please report it so that it gets corrected in the next reprint.

Best regards,
Peter

View solution in original post

Sorry for the inconvenience, it is indeed listed in the Errata.
Thank you for your help.
Peter Paluch
Hall of Fame Cisco Employee

Hi Bastien,

There was no inconvenience at all! It was a pleasure to clarify this issue. Thank you for confirming that the book errata already know about this.

Best regards,
Peter

"What I suggest doing is visiting the Cisco Press website, locating the particular book, and checking the published errata - perhaps this one is already known and recorded. If not, please report it so that it gets corrected in the next reprint."

Valuable suggestions, not many would probably think of. I suspect you being a Cisco Press book[s] co-author helps. ;)
Peter Paluch
Hall of Fame Cisco Employee

Joe,

Valuable suggestions, not many would probably think of. I suspect you being a Cisco Press book[s] co-author helps. ;)

Guilty as charged :) Thank you!

Best regards,
Peter