Special Sub-Topic: The OSI Reference Model Click Here To Play: The OSI Reference Model

What does the acronym OSI stand for?

Open System Interconnection. The OSI reference model is used as a guide for teaching and understanding the way networks operate.

There are seven layers in the OSI model. Which of the following is the correct order?

Application, Presentation, Session, Transport, Network, DataLink, Physical. An easy way to remember the order of the layers is: A-ll P-eople S-eem T-o N-eed D-ata P-rocessing

At which layer of the OSI model is a path decision made based upon an IP address?

Network. At the network layer, data is transported in the form of a packet.

Which of the following takes place at the presentation layer?

Encryption. The presentation layer encrypts data to be sent across the network, and decrypts it so it can be accessed by the application layer on the receiving end.

Which is NOT a function of the Application layer?

Windowing. Quality of Service and user authentication are also handled by the application layer.

Data is transported in bits at the Physical layer.

t. A bit is simply a binary digit. Either a 0 or a 1.

Data is transported in segments at the Data Link layer.

f. At the data link layer, user data is encapsulated in a frame.

Which layer of the OSI model contains the LLC sublayer and the MAC sublayer?

Data Link Layer. The LLC and MAC sublayers allow for different layer 2 protocols to be used, such as Ethernet, Token Ring and FDDI.

The Session Layer is layer 7 of the OSI Model.

f. The Session layer is layer 5. It provides synchronization for voice and video connections.

Communication at the Transport layer is connectionless.

f. The Transport Layer provides connection orientated communication. TCP and SPX are examples of connection orientated protocols at Layer 4.