350-001 415Q Q114 答案是否有誤?

supisces

QUESTION 114
3 V! O2 X9 q- W% }Loop guard and UniDirectional Link Detection both protect against Layer 2 STP loops. In which two ways does loop guard differ from UDLD in loop detection and
9 B" f) z# p/ d4 U/ vprevention? (Choose two.)

A. Loop guard can be used with root guard simultaneously on the same port on the same VLAN while UDLD cannot.
B. UDLD protects against STP failures caused by cabling problems that create one-way links.
; x3 |) A9 v! I  Z. S9 K& H( uC. Loop guard detects and protects against duplicate packets being received and transmitted on different ports.
D. UDLD protects against unidirectional cabling problems on copper and fiber media.
E. Loop guard protects against STP failures caused by problems that result in the loss of BPDUs from a designated switch port.

Answer: BE
; `" |2 N2 \6 U  L% v
5 C& x; F+ t# p8 Q, x7 G答案 E 沒有爭議

) c8 z( R3 ~/ Y( e認為答案不是 B 的人說, 官方的書裏 Switching volume 1 page 213 提到 B 的功能同時可被兩者提供.
(誰有書可以證實一下的?)
" X+ `# q8 Q0 n$ \- q% F8 N
認為答案是 D 的人說,
UDLD的运行分为两种模式：normal (默认) 和aggressive。Normal模式只能检测光纤上的单向链路故障，而aggressive模式不仅能够检测光纤上的单向链路故障，还能检测双绞线上的单向链路故障。
http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_58_se/configuration/guide/swudld.html

不知道大家有甚麼看法?


4 g; A& ?0 r& p. @. d

redfield

搭车问一下111题，答案是没有端口block，但是怎么看应该是有两个端口会block的，有没有人来解答一下

prince786

Thank you so so much 111111111111111111111111111111111111111

supisces

redfield 发表于 2012-7-15 15:56
: J# Z! }5 y4 b% K搭车问一下111题，答案是没有端口block，但是怎么看应该是有两个端口会block的，有没有人来解答一下

Q112 嗎?
MST 有兩棵樹,
在某棵樹是 block 的端口, 在另一棵樹不會是 block..

5ibob

夏天的微风

虽然不懂，但是给楼主顶上去~~

user_cisco

不用软件翻译一下， 有的东西还真看不懂， 帮你顶上去。

brian0711

windmonster