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中级工程师
   
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楼主 |
发表于 2016-7-3 13:46:09
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在麻烦各位看227Q中的52题4 i. l& x6 o& M7 P4 n( J
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52.Which two security risks can occur with PMTUD? (Choose two)
6 }' W$ O( w4 R. QA. An attacker can block valid Datagram Too small messages, to cause a DDos. z6 m9 j d$ e
50.Refer to the exhibit.7 O' ]" [, Z& h8 v& P2 T3 R
Which kind of ICMPv6 packet is shown in the output?, f5 H3 T' X, H4 {0 W9 z$ |
B. An attacker can block valid Datagram Too small messages, to cause a Dos.* ^* E, J) ~. u, q E% J' Q1 D
C. An attacker can slow data flow by sending false messages that indicate that the PMTU is significantly smaller than the true PMTU.
; L% U9 C8 Q" u4 K, c# C: D5 vD. An attacker can cause data lost by sending false messages that indicate that the PMTU is significantly smaller than the true PMTU.
5 F- h( P$ J, x9 D9 r1 QE. An attacker can cause data lost by sending false messages that indicate that the PMTU is significantly larger than the true PMTU./ h( k9 l* ? I6 V
F. An attacker can slow data flow by sending false messages that indicate that the PMTU is significantly larger than the true PMTU.
, b& p: }$ ]/ c* W i! b9 _Answer: BD' T1 x1 p! W0 L# b
F4 j n, W* ?8 R% q0 p* h我觉得答案应该选E,而非选D2 [. u1 g0 _( B8 {# B& U9 C, V
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6 ?" y" g. |, G( Y3 j, T' jPMTU(Path MTU,路径最大传输单元)是在源节点和目的节点之间的路径上的任一链路所能支持的链路MTU的最小值。
" B1 [9 Y+ |' ^: q, U6 |& Y$ l在IPv6网络中,分段不在中间路由器上进行。当需要传送的数据报文长度比链路MTU大时,只由源节点本身对数据报文进行分段,中间路由器不对数据报文进行再次分段。这就要求源节点在发送数据报文前能够发现整个发送路径上的所有链路的最小MTU,然后以该MTU值发送数据报文,这就是PMTU发现。 |
11#
2016-7-3 13:46:09
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