VTP pruning does not prune extended?

[George-Sl]

According to this fact the answer C is incorrect, and answer D is right,
Am I right??

VTP pruning takes effect several seconds after you enable it. VTP pruning does not prune traffic from VLANs that are pruning-ineligible. VLAN 1 and VLANs 1002 to 1005 are always pruning-ineligible; traffic from these VLANs cannot be pruned. Extended-range VLANs (VLAN IDs higher than 1005) are also pruning-ineligible.

A network engineer is extending a LAN segment between two geographically separated data centers. Which enhancement to a spanning-tree design prevents unnecessary traffic from crossing the extended LAN segment?
A. Modify the spanning-tree priorities to dictate the traffic flow.
B. Create a Layer 3 transit VLAN to segment the traffic between the sites.
C. Use VTP pruning on the trunk interfaces.
D. Configure manual trunk pruning between the two locations.

[Borgenstrand]

Hi,

due to the wording enhancement to a spanning-tree design, I would have to say C. Manual pruning is not enhancement in this regard I believe. It would work to do it manually though.

[paul driver]

Hello

if ithis question does mean to relate to stp and logical instances I would say the answer is D as manual vtp pruning as I understand DOES reduce the total number of stp logical instances - However answer C which is dynamic pruning will NOT perform this action.

Res

Paul

[Borgenstrand]

Hi, I do agree that both C and D would work. The question does not say anything if it is just about the traffic itself or the BPDUs as well. If VTP pruning is enabled, the traffic would not go over if it does not need to, the BPDUs will still be sent over though. 

I do not know if the question is about the BPDUs or just the VLAN traffic itself, nor do I know if it is about automatic versus manual control of the traffic flow. Because it only says unnecessary traffic, it could be both C and D.

[Joseph W. Doherty]

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Posting

No, your fact, alone, doesn't make C incorrect, because the exceptions aren't mentioned in the question.  However, D is likely a better answer than C, because it bypasses the restrictions you note and we don't know if VTP is even active.

[acampbell]

Gents,

Sorry to wake this one up again.

I think this from the CCNP/Switch exam

Anyway here is an extract from the CCNP study guide in the VTP section

I think the question is trying to get at spanning-tree not VTP

Tip
Even when VTP pruning has determined that a VLAN is not needed on a trunk,
an instance of the Spanning Tree Protocol (STP) will run for every VLAN that is allowed
on the trunk link. To reduce the number of STP instances, you should manually “prune”
unneeded VLANs from the trunk and allow only the needed ones. Use the switchport
trunk allowed vlan command to identify the VLANs that should be added or removed
from a trunk.

So for me "D" is the right answer.

Regards

Alex

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages wha2tsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Again with regard to the question, the question doesn't tell us if STP is active, or if active, what "flavor" is being used.  (Consider if MST was being used, there might only be one or two instances of active STPs.)

Like the VTP other limitations, I wouldn't say Alex's observation, alone, makes "D" the right answer, but it too makes "D" a better answer.  Again, manual pruning avoids all these "gotchas" you might run into with VTP pruning.

Oh, and on the subject of VTP pruning "gotchas", I believe VTP prunes if the next immediate device doesn't have any ports in a VLAN, which is a problem is there are any devices another hop away which have need for that VLAN.