下面的组件中，（）是置于不同网络安全域之间的一系列部件的组合，是不同网络安全域问通信流的唯一通道，可以根据企业有关的安全策略控制进出网络的访问行为。 代理服务器。 VPN服务器。 防火墙。 入侵检测系统。
《特种设备安全监察条例》中规定的特种设备是（） 起重机械。 压力容器。 场（厂）内专用机动车辆。 客运索道。
Network topology exhibit： You work as a network administrator at . You study the network topology exhibit carefully. is a small company that has an existing enterprise network consisting of two switches named 1 and 2. The network topology schemata indicates their layer 2 mapping. VLAN 40 is a new VLAN that will be used to provide the shipping personnel access to the server. For security reasons， it is necessary to restrict access to VLAN 20 in the following manner： Users connecting to 1’s port must be authenticate before they are given access to the network. Authentication is to be done via a Radius server： Radius server host： 172.120.39.46 Radius key： key Authentication should be implemented as close to the host device possible. Devices on VLAN 20 are restricted to in the address range of 172.120.40.0/24. Packets from devices in the address range of 172.120.40.0/24 should be passed on VLAN 20. Packets from devices in any other address range should be dropped on VLAN 20. Filtering should be implemented as close to the server farm as possible. The Radius server and application servers will be installed at a future date. You have been tasked with implementing the above access control as a pre-condition to installing the servers. You must use the available IOS switch features.
Internet起源于美国的（）网络。
What is the purpose of session management？（） To manage the user’s login and logout activities.。 To store information on the client-side between HTTP requests.。 To store information on the server-side between HTTP requests.。 To tell the web container to keep the HTTP connection alive so it can make subsequent requestswithout the delay of making the TCP connection.。
空中交通管制单位为飞行中的民用航空器提供的空中交通服务中含有（）
