350-401 · Question #197
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?
The correct answer is A. It remains in err-disabled state until the shutdown/no shutdown command is entered in the. 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.
Question
Exhibits
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
How the community answered
(58 responses)- A81% (47)
- B5% (3)
- C3% (2)
- D10% (6)
Why each option
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.
The `no spanning-tree bpduguard enable` command only disables the BPDU Guard feature for future events on interface Fa 1/0/7; it does not clear the existing err-disabled state, which requires a manual `shutdown` followed by `no shutdown` to recover the port.
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`.
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.
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
Source: 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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