ccna 题库 291 A选项是不是也对

Shalltear

QUESTION 291

Which condition does the err-disabled status indicateon an Ethernet interface?

A. There is a duplex mismatch.

B. The device at the other end of the connection ispowered off.

C. The serial interface is disabled.

D. The interface is configured with the shutdowncommand.

E. Portsecurity has disabled the interface.

F. The interface is fully functioning.

题库答案 E 外国论坛水友质疑选 A 也对

依据 cisco 官网

There are various reasons for the interface to go into errdisable. The reason can be:
Duplex mismatch
Port channel misconfiguration
BPDU guard violation
UniDirectional Link Detection (UDLD) condition
Late-collision detection
Link-flap detection
Security violation

wyang9311

A 和 E 都正确。但是在准备考试时，会遇到“正确答案“ 和“思科答案“的困扰。如果两个都对，上下文又没有做详细的背景交待，怎么办？ 窃以为，还是要找思科答案。

对本题， 我选 E。因为思科官网将此列为err-disabled status 第一个例子来做解释， 尽管后面也介绍了其他可能发生的原因。 详见 http://www.cisco.com/c/en/us/sup ... sable-recovery.html

Q9966

虽然A可能是正确的，E是比A更好的答案。一般的策略是选择最好的答案。