问一个tcp的问题（知道过程，不知道怎么称呼）

13: When using TCP, after a session is open, the applications can adjust the number of segments they receive before sending an acknowledgment. This behavior is known as ______________.

　　A. MTU adjustment

　　B. Windowing

　　C. Flexible Send Path

　　D. FCS

再一个问题：

23: Your junior network administrator cannot seem to ping a host in another network and asks you why it isn't working. Which of the following is not an answer that you would give him?

　　A. The host's default gateway is down.

　　B. The destination host is not powered on.

　　C. The IP address of the router interface is incorrect.

　　D. The IP address of the switch to which the destination host connects is incorrect.

　　E. The host is in a different subnet.

答案D的翻译：因为目标主机所连交换机的ip地址是非法的。
答案E的翻译：这个主机在不同的子网内。

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问题问的不是这个问题的结果。D和E都应该是正确的，单这个问题是个单选题，怎么选择答案？？

现在较疑惑的是交换机的地址应该是交换机的管理地址，管理地址难道影响网络的连通？？

网盲路过
incorrect这个词，怎么样ip的才算incorrect呢？