关于题库里的一道DTP的题

abjoint

The network administrator is trying to add Switch1 to the network, but the 802.1Q trunk is not coming up. Switch1 was previously tested in the laboratory and its
4 R: R  H) ^. g; [: ctrunk configuration worked fine. What are three possible causes of this problem? (Choose three)
A. The trunking configuration mode on Switch1 is set to Off.
0 Z6 n% e; M7 k1 U+ qB. The trunking configuration mode on the other end is set to On.
  X% S1 l6 K+ j8 H5 |6 r7 t6 KC. The trunking configuration mode on the other end is set to Desirable.
' i: b) R' p5 N, ~% T% }' `D. Cisco Discovery Protocol is not running on the other end.
6 c1 a8 W5 d7 p3 I3 ME. There is a VTP domain name mismatch.
- l2 p! j  x1 P$ S7 f6 I: |F. Switch1 does not support 802.1Q.

/ c. T0 Z$ w6 z5 |2 l  T8 U; C6 q之前的答案里都是CEF或BCE，不过我觉得应该是ACE

( A' X' L- v! q8 S9 G  NA，在官网http://www.cisco.com/en/US/products/hw/switches/ps4324/products_tech_note09186a0080094713.shtml里提到off就是Puts the port into permanent non-trunking mode.
3 B4 O) j  A1 ]7 B; l7 IB，如果对端为trunk=on，switch1除了off都能起trunk。因为选了A，所以这里认为switch1不会是off。那么B不对。
C，如果对端为Desirable，switch1在on, desirable, 或 auto都能起trunk，那么如果switch是Nonegotiate ，那么就不能建立trunk
- {: n' n; }) m. ID，CDP和这个没关系
E，VTP域名不一致将无法成功协商trunk。
F，虽说不支持802.1Q当然不行，但从实际上看，cisco肯定支持1Q（我不知道哪款不支持）。另外在实验室环境测试是好的，我认为这里不会忽略掉1q的测试。
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iceyorange

huangtidi

bain8848

BCE吧， A肯定不对，因为之前sw1在实验室里起过trunk,所以肯定不是OFF

1988

BCE

aili_tree

nashn21

whtzmkm

纸纸纸

wyayz

应该是CEF

itxphu

这题在489q里面是AEF，在504Q里面却是BCE，有高人解析一下么？谢谢