In the following four descriptions, which one is correct? () A: If<br/>one host’s transport layer uses TCP, then its network layer<br/>must use virtual-circuit network. B: Datagram<br/>network provides connection service C: The<br/>transport-layer connection service is implemented in the router D: The<br/>network-layer connection service is implemented in the router as well<br/>as in the end system.

The WDM transmission network consists of three layers: Physical Layer、Data Link Layer and Network Layer.

The IoT system consists of three layers:, and A: sensing layer B: transport layer C: network layer D: application layer

P12: ___________ work at the Network Layer(layer 3) of the OSI model and the Internet Layer of TCP/IP. A: Switches B: Routers C: Hubs D: Modems

In the seven-layer OSI network architecture, ( ) layer is on point-to-point basis A: Network B: Transport C: Session D: Application

A typical neutral network includes layer, hidden layers and output layer.

如下图，一名管理员ping默认网关发现如下输出，最有可能是那一层OSI出问题？（） A: data link layer B: application layer C: access layer D: session layer E: network layer

In the network layer, the transmission is ( ). A: bit stream B: message C: packet D: frame

ISO/OSI七层模型中，提供端到端的透明数据传输服务，差错控制和流量控制的层是（ ） A: Physical Layer B: Network Layer C: Transport Layer D: Session Layer

What is the name of a network-layer packet? （ ） A: message B: segment C: datagram D: frame