OSI Model

Question 1

Layer 7: Application
Function/responsibilities (3)

Answer 1

Function: Interface between the end-user and the network. Provides services for network-aware applications.

Responsibilities:

1 Provides network services to end-users.

2 Initiates communication.

3 Supports application protocols like email, file transfer, and web browsing.

Question 2

Layer 6: Presentation
Function/Responsibilities(3)

Answer 2

Function: Translates data between the application and the network.

Responsibilities:

1 Data translation, encryption, and compression.

2 Converts data formats (e.g., EBCDIC to ASCII).

3 Ensures data from the application layer of one system is readable by the application layer of another.

Question 3

Layer 5: Session
Function/Responsibilities(3)

Answer 3

Function: Manages and controls the dialog between two computers.

Responsibilities:

1 Establishes, manages, and terminates sessions (conversations).

2 Keeps track of dialog control (who transmits and when).

3 Handles synchronization and checkpointing.

Question 4

Layer 4: Transport
Function/Responsibilities(4)

Answer 4

Function: Provides data transfer between end systems.

Responsibilities:

1 Segmentation and reassembly of data.

2 Flow control and error correction.

3 Ensures complete data transfer with acknowledgments.

4 Provides both reliable (TCP) and unreliable (UDP) communication.

Question 5

Layer 3: Network
Function/Responsibilities(2)

Answer 5

Function: Determines how data is sent to the receiving device over multiple networks.

Responsibilities:

1 Routing, forwarding, and logical addressing (IP addresses).

2 Handles packet delivery, including across routers.

Question 6

Layer 2: Data Link
Function/Responsibilities(3)

Answer 6

Function: Responsible for reliable transmission of data across a single link or local network.

Responsibilities:

1 Handles MAC addresses.

2 Provides framing, error detection, and sometimes correction.

3 Divided into:

3a Logical Link Control (LLC)

3b    Media Access Control (MAC)

Question 7

Layer 1: Physical
Function/Responsibilities(3)

Answer 7

Function: Physically transmits raw binary data over a medium.

Responsibilities:

1 Defines hardware specifications.

2 Manages electrical, optical, or radio signals.

3 Defines pin layouts, voltage levels, cable types.

Question 8

What is the OSI Model?

Answer 8

A framework for how networked devices send, receive and interpret data.

Question 9

What are the seven layers?

Answer 9

1 Physical
2 Data Link
3 Network
4 Transport
5 Session
6 Presentation
7 Application

Question 10

How to remember the layers.

Answer 10

People Depend On Networks To Send Packets Accurately