Refer to the exhibit. The command spanning-tree guard root is configured on interface Gi0/0
on both switch S2 and S5. The global configuration command spanning-tree uplinkfast has
been configured on both switch S2 and S5. The link between switch S4 and S5 fails. Will
Host A be able to reach Host B?
A.
Yes. Traffic can pass either from switch S6 to S3 to S2 to S1, or, from switch S6 to S5 to
S2 to S1.
B.
No. Traffic will pass from switch S6 to S5 and dead-end at interface Gi 0/0.
C.
No. Traffic will loop back and forth between switch S5 and S2.
D.
Yes. Traffic will pass from switch S6 to S3 to S2 to S1.
E.
No. Traffic will either pass from switch S6 to S5 and dead-end, or traffic will pass from
switch S6 to S3 to S2 and dead-end.
Brilliant explanation.
Here is mine. First stupid topology. Uplink fast must only be used on Access switches not distribution nor core.
Anyway. We don’t know which switch is the root. Could be any switch in the topology. Again doesn’t matter. S2 or S5 will have a better path to the root bridge and will try to advertise it through the S2 – S5 link. Since root guard is enable on that link, it will always be blocked by either S2 or S5. This link will never (ever) be used. So the only path is S6 S3 S2 S1
hope this helps