从对信息的破坏性上看，网络攻击可以分为被动攻击和主动攻击，以下属于被动攻击的是（ ） 。
答案选择B。
网络攻击是指针对计算机系统、基础设施、网络或个人设备的任何类型的进攻。主要为：破坏、修改、使软件/服务功能丢失、非授权情况下获取/访问数据等
主动攻击可分为篡改、DOS等
被动攻击一般不对数据进行篡改、只是在非授权情况下，获得相关数据和信息；通常分为：窃听、流量分析、破解加密的数据流等方式
结合题干来看，选项B属于被动攻击
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答5处
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答4处
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答3处
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答2处
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答1处
管理员要检查本地主机TCP/IP协议是否能够正常工作，应使用下面（ ）命令。
在Windows系统中，可以在“运行”对话框中使用（ ）打开命令行窗口。
在Windows 系统中，要持续ping某主机，应使用（ ）选项。
在Linux系统中，管理员在DHCP服务器的配置文件中添加了下面一段代码:subnet 192.168.20.0 netmask 255.255.255.0{range 192 .168 .20 .10 192 .168 .20.50;option domain-name-server ns1 .internal.example.comoption routers 192 .168 .20.254;option broadcast-address 192.168.20.255;default-lease-time 1200;max-lease-time 360000;}当该DHCP服务器启动后，下面分配给客户端的IP地址中，正确的是（ ）.
在Linux系统中，通常使用（ ）为用户提供FTP服务，其配置信息存放在（回答此处）目录中。
