If a switch port goes directly into a blocked state only when a superior BPDU is received, what mechanism must be in use?
A. STP BPDU guard
B. loop guard
C. STP Root guard
D. EtherChannel guard
What mechanism must be in use?
If a switch port goes directly into a blocked state only when a superior BPDU is received, what mechanism must be in use?
A. STP BPDU guard
B. loop guard
C. STP Root guard
D. EtherChannel guard
I agreed with those who have chosen C.. the Key word is Block .. root guard place the port on blocking state while BPDU guard place on Disabling state.
c is the correct answer because the port goes in blocked state if revived superior BPDU the solution is to use root guard so the port can go into root inconsistent state ——– it is A very tricky Question
This must be one of the trickiest Cisco exam questions.
The following is from Cisco:
BPDU guard and root guard are similar, but their impact is different. BPDU guard disables the port upon BPDU reception if PortFast is enabled on the port. The disablement effectively denies devices behind such ports from participation in STP. You must manually reenable the port that is put into errdisable state or configure errdisable-timeout.
Root guard allows the device to participate in STP as long as the device does not try to become the root. If root guard blocks the port, subsequent recovery is automatic. Recovery occurs as soon as the offending device ceases to send superior BPDUs.
Is it A or is it C?…..
I think the key in the question is the part that says superior BPDU, no just BPDU for that reason i think the correct answers is C
STP Root guard will make the interface into root-inconsistent and the state of the interface will be blocked.
BPDU guard will make the port into disabled (error-inconsistency) not the blocked
so answer is “c”
The confusion with the question is the definition of blocked state.
When you think of blocked state most people think of disabled state.
Cisco’s definition of blocked state in this case is blocking,listening & waiting for the superior BPDU’s to cease.
Inconsistent state does just that.
BPDU Guard puts the state into DISABLED not blocked.
Answer is root guard (C)
question is about ONLY when a Superior BPDU changes the port state. The only mechanism that changes a port to a “block” sate when a SUPERIOR BPDU is received is the STP root guard to protect the functionality of the root election.
Correct answer is C
The answer is C- Root Guard
http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/10588-74.html#diff
stp root gaurd leaves the interface into root-inconsistent state which is like stp listen state with that being said and since the question is about blocked state then A is correct answer
Should be answer C – STP root guard