In the 7-layer OSI model, which layer

1、At which layers of the OSI model do WA

At which layers of the OSI model do WANs operate?（）A application layerB session layerC transport layerD network layerE datalink layerF physical layer

2、At which layers of the OSI model do WA

At which layers of the OSI model do WANs operate (Choose two.)（）。Aapplication layerBsession layerCtransport layerDnetwork layerEdatalink layerFphysical layer

3、Which three of the following OSI model

Which three of the following OSI model layers also belong to the TCP/IP model?（）A The application layerB The session layerC The data link layerD The transport layerE The network interface layerF The physical layer

4、Which layer of the OSI reference model

Which layer of the OSI reference model uses the hardware address of a device to ensure message delivery to the proper host on a LAN?（）A physicalB data linkC networkD transport

5、At which layer of the OSI model is the

At which layer of the OSI model is the optimal path to a network destination determined at?（）A Data LinkB SessionC PhysicalD PresentationE NetworkF Transport

6、Which OSI layer is associated with the

Which OSI layer is associated with the following: The acknowledgement of transmissions, sequencing, and flow control across a network?（）A Layer 2B Layer 3C Layer 4D Layer 5E Layer 6F Layer 7