[3.1] Protocols, Reference Models, Data Encapsulation and Access

Which of the following are benefits of using a layered model in networking? (Multiple Answers)

• It assists in protocol design by defining clear interactions between layers (simplification)

• It encourages vendor competition by allowing interoperability

• It ensures changes in one layer affect all others for faster adaptation

• It provides a common language to describe networking functions

• It prevents technology or capability changes in one layer from affecting other layers
  above and below

Which layer of the OSI model is responsible for data formatting?

• 3 - Network layer

• 7 - Application layer

• 6 - Presentation layer

• 4 - Transport layer

Answer explanation

6 - Presentation -> common representation of the data transferred between application
layer services

7 - Application -> Contains protocols used for process-to-process communications

5 - Session -> Provides services to the presentation layer and to manage data exchange.

4 - Transport -> Defines services to segment, transfer, and reassemble the data for individual
communications

Which layer of the OSI model is responsible for error detection?

• 3 - Network layer

• 2- Data Link layer

• 4 - Transport layer

• 7 - Application layer

Answer explanation

Layer 2 (Data Link) is responsible for error detection and correction of data as it travels between two devices on the same network

What is the primary function of the Application layer in the OSI model?

• To manage data flow

• To provide process-to-process communication

• To format data for transmission

• To route packets

Answer explanation

Layer 7 (Application) provides services to the user or applications (like web browsers, email apps).

What is the function of the Session layer in the OSI model?

• To provide end-to-end communication

• To route packets

• To format data for transmission

• To manage data exchange

Answer explanation

Layer 6 (Session) formats and translates data so the application can understand it (like converting file types or encrypting data).

Which of the following is a characteristic of the OSI model?

• It has four layers

• It does not support routing

• It is a proprietary model

• It is used for standardizing network communication

What is the purpose of the Network layer in the OSI model?

• To provide a common representation of data

• To encrypt data

• To manage data flow

• To route packets

Answer explanation

Network Layer (Layer 3) deals with source and destination IP addresses.

Which layer breaks data into segments and ensures reliable delivery?

• Layer 7

• Layer 6

• Layer 4

• Layer 3

Answer explanation

From 7 -> 1:

All People Seem To Need Data Processing

7 - Application

6 - Presentation

4 - Transport (breaks data into segments)

3 - Network

At which OSI layer are MAC addresses used?

• 3 - Network

• 2 - Data Link

• 4 - Transport

• 5 - Session

Answer explanation

From 7 -> 1:

All People Seem To Need Data Processing

At which layer of the OSI model would a logical address be added during encapsulation?

• 1 - Physical

• 2 - Data Link

• 4 - Transport

• 3 - Network

Answer explanation

logical address = IP address