350-401 Question #197: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. An engineer entered the command no spanning-tree bpduguard enable on interface Fa 1/0/7. What is the effect of this command on Fa 1/0/7?

Options

• AIt remains in err-disabled state until the shutdown/no shutdown command is entered in the
• BIt remains in err-disabled state until the errdisable recovery cause failed-port-state command is
• CIt remains in err-disabled state until the no shutdown command is entered in the interface
• DIt remains in err-disabled state until the spanning-tree portfast bpduguard disable command is

Explanation

Disabling BPDU Guard on an interface currently in an err-disabled state does not automatically recover it; the interface will remain err-disabled until it is manually reset using the shutdown followed by no shutdown commands.

Common mistakes.

• B. The errdisable recovery cause failed-port-state command is not the correct or standard Cisco IOS command for recovering from a BPDU Guard err-disabled state; the appropriate cause is typically bpduguard.
• C. Simply entering no shutdown after a port is err-disabled is often insufficient for recovery; a shutdown command is usually needed first to completely reset the interface state before no shutdown can bring it back up.
• D. The command spanning-tree portfast bpduguard disable is not a valid or appropriate command for recovering an err-disabled port; the correct command for controlling BPDU Guard is spanning-tree bpduguard enable or no spanning-tree bpduguard enable.

Concept tested. BPDU Guard err-disable recovery

Reference. https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_55_se/configuration/guide/3560scg/swstp.html#wp1074092

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