OSI Reference Model

Question 1

OSI Reference model

Answer 1

Provides a means of describing how data is transmitted over a network. The model addresses hardware, software, and data transmission.

Question 2

Physical Layer (Layer 1)

Answer 2

Defines certain specifications (for example, electrical, mechanical, procedural, and functional). Physical layer specifications are defining characteristics.

Question 3

Data Link Layer (Layer 2)

Answer 3

Defines how data is formatted for transmission and how access to physical media is controlled. This layer also typically includes error detection and correction to ensure reliable delivery of the data.

Question 4

Network Layer (Layer 3)

Answer 4

Provides connectively and path selection between two host systems that may be located on geographically separated networks. The network layer is the layer that manages the connectivity of these users by providing logical addressing.

Question 5

Transport Layer (Layer 4)

Answer 5

Defines services to segment, transfer, and reassemble the data for individual communications between the end devices. TCP and UDP are the protocols that operate at this layer.

Question 6

TCP

Answer 6

Is used when data loss cannot be tolerated (file transfer).

Question 7

UDP

Answer 7

Is used when some data loss is acceptable (when speed is more important then accuracy; for video streaming.

Question 8

Section Layer (layer 5)

Answer 8

Establish, manages, and terminates session between two communicating hosts. The session layer also synchronizes dialog between the presentation layers of the two hosts and manages their data exchange. In addition to session regulation, the session layer offers provisions for efficient data transfer, CoS (Class of Service), and exception reporting of session layer, presentation layer, and application layer problems.

Question 9

Presentation Layer (Layer 6)

Answer 9

Ensures that the information that is sent at the application layer of one system is readable by the application layer of another system. The presentation layer has to translate among multiple data formats using a common format.

Question 10

Application Layer (Layer 7)

Answer 10

This layer provides network services to the applications of the user, such as email, file transfer, and terminal emulation. It only provides services only to application outside the OSI Model. The application layer establishes the availability of intended communication partners. It then synchronizes and establishes agreement on procedures for error recovery and control of data integrity.