单选题下列命令片段含义是()Huaweisystem-view[Huawei]observe-port1interfacegigabitethernet0/0/1[Huawei]interfacegigabitethernet0/0/2[Huawei-gigabitethernet0/0/2]port-mirroringtoobserve-port1inbound
单选题在防火墙域间安全策略中，不是outbound方向数据流的是_
单选题下列关于IEEE802.11a的描述中，不正确的是（ ）。
单选题在SNMP协议中TRAP上报是通过UDP协议的（ ）端口。
单选题A 从证书颁发机构 X1 获得证书，B 从证书颁发机构 X2 获得证书。假设使用的是 X509 证书，X2《X1》表示 X2 签署的 X1 的证书，A 可以使用证书链来获取 B 的公钥，则该链的正确顺序是（）。
单选题模拟信号数字化的正确步骤是（）。
单选题某主机的MAC地址为00-FF-12-CD-10-22，其IP地址配置选项设置为“自动配置”，该主机可通过发送( 回答此处)报文以查找DHCP服务器，并请求IP地址配置信息，报文的源MAC地址是( )，源IP地址是( )。
单选题某信息系统内网IP为10.0.10.2，域名解析的公网IP为113.201.123.14，现需要在出口防火墙配置NAT，使得外部用户能正常访问该系统。其中：NAT模式应配置为( )，源地址应配置为( 回答此处)。
单选题以下关于路由协议的叙述中，错误的是_ _。
单选题在DNS服务器中，区域的邮件服务器及其优先级由（ ）资源记录定义。
单选题在千兆以太网标准中，采用屏蔽双绞线作为传输介质的是（ 此空作答 ），使用长波1330nm光纤的是（ ）。
单选题Network frewalls are security devices used to stop or mitigate (回答此处) access to private networks connected to the Internet, especially intranets. The only trafle alowed on thev network is defined via firewall ( )-any other taff attempting to access the network is blockeD. Network firewalls sit at the ( ) line of a network, acting as a communicationsliaison between intemal and gxtemal devics, When properly configured, a firewall alws users to access any of the resources they need while simultaneously keeping out unwanted accesses. In addition to limiting access to a protected computer and network, a firewall can ( ) all traffit coming into or leaving a network, and manage remote access to a private network through secure authentication grtificates and logins. ( ) firewalls examine every packet that passes through the network and then accep or deny it as defined by rules set by the user.
单选题6to4是一种交持IPv6站点通过IPv4网络进行通信的技术，下面IP地址中（ ）属于6to4地址。
单选题主机A的主域名服务器为202．112．115．3，辅助域名服务器为202．112．115．5
单选题IP数据报首部中IHL(Internet首部长度)字段的最小值为(65)______________
单选题下列属于网络安全等级保护第三级且是在上一级基础上增加的安全要求是（ ）。
单选题某工厂使用一个软件系统实现质检过程的自动化，井逐步替代人工质检，该系统属于 。
单选题lA network attack is an attempt to gain（）access to an organization’s network,with the objective of stealing data or performing other malicious activities.Plagiarism is A（作答此空）-of-service（DoS）attack is a cyber-attack in which the attacker seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to a network.In the case of a simple attack,a（）could have a simple rule added to deny all incoming traffic from the attackers,based on protocols,ports,or the originating IP addresses.In a（）DoS（DDoS）attack ，the incoming traffic flooding the victim originates from（）different sources.This effectively makes it impossible to stop the attack simply by blocking a single source.
单选题在风险管理中，降低风险危害的策略不包括（）。