正确答案: B

数据链路层

题目：VLAN tag在OSI参考模型的（ ）实现。

解析：VLAN tag是在数据链路层实现的。

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学习资料的答案和解析：

[单选题]● POP3服务默认的TCP 端口号是（70）。（70）

110

解析：试题（70）分析

[多选题]●Extreme Programming (XP) is a discipline ofsoftware development with__(71) of simplicity, communication, feedback and courage. Successful software development is a team effort - not just the development team, but the larger team consisting of customer, management and developers. XP is a simple process that brings these people together and helps them to succeed together. XP is aimed primarily at object-oriented projects using teams of a dozen or fewer programmers in one location. The principles of XP apply to any (72) project that needs to deliver quality software rapidly and flexibly.An XP project needs a (73) customer to provide guidance. Customers, programmers, managers, are all working (74) to build the system that's needed. Customers - those who have software that needs to be developed - will learn simple, effective ways to (75)what they need, to be sure that they are getting what they need, and to steer the project to success.

importance

keys

roles

values

small-sized

moderately-sized

large-sized

huge-sized

part-time

casual

seldom

full-time

together

by themselves

separately

alone

tell

know

communicate

feedback

解析：D,B,D,A,C

[多选题]生产企业有()行为，视为未经许可出售安全专用产品，由公安机关根据《中华人民共和国计算机信息系统安全保护条例》的规定予以处罚。

没有申领销售许可证而将生产的安全专用产品进入市场销售的

安全专用产品功能发生改变，而没有重新申领销售许可证进行销售的;销售许可证有效期满，未办理延期申领手续而继续销售的

提供虚假的安全专用产品检测报告或者虚假的计算机病毒防治研究的备案证明，骗取销售许可证的;销售的安全专用产品与送检样品安全功能不一致的

解析：答案：ABCD

[单选题]

B． 保密性不如DES C． 可用于对不同长度的消息生成消息摘要 D． 可以用于数字签名

可以用于数字签名

[单选题]FCC规定，专业安装人员在增加天线增益时应保持发射功率的增益比率为多大?A、3:1

[单选题]判断题：客户端可以看见VLAN。

错误