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A. The application layer

B. The session layer

C. The data link layer

D. The transport layer

E. The network interface layer

F. The physical layer

A、Entity

B、Bean

C、Presentation

D、None of the above

A、Bit encoding and decoding.

B、Error control.

C、Datagram fragmentation.

D、Out of order receipt of packets.

Which OSI layer does a Bridge operate at？ ()

A．the Physical Layer

B．the Data Link Layer

C．the Transport Layer

D．the Network Layer

Which OSI layer does a Router operate at？

A．the Physical Layer

B．the Data Link Layer

C．the Transfer Layer

D．the Network Layer

A．Application

B．Internet

C．Transport

D．Network

E．Data Link

A．Bean layer

B．Mediatior layer

C．Entity layer

D．Resource layer

A. Application Layer

B. Presentation Layer

C. Data Link Layer

D. Physical Layer

A. A proxy server

B. A load balancer

C. A layer two switch

D. A multilayer switch

A．Network（layer three）

B．Transport（layer four）

C．Data link（layer two）

D．Session（layer five）