OSI Model

28 Questions

What is the primary purpose of using a reference model in networking?

To understand how devices interact with each other

What is the Open Systems Interconnect model commonly known as?

OSI model

What is the primary concern of the physical layer in the OSI model?

Getting bits on the wire

What is an example of something you might see at layer one of the OSI model?

Fiber optic cable

What is the name given to data at different layers of the OSI model?

Not specified in the video

Why is the OSI model not revered as the end-all, be-all of networking?

It is not a perfect model

What is represented by light in the fiber optic cable example?

Binary zeros and ones

What is the number of layers in the OSI model?

Seven

What is the primary function of the session layer?

Session establishment, maintenance, and termination

What is the purpose of the presentation layer?

To format data into a readable format

What protocol is used to set up and maintain voice or video calls?

SIP

What is the purpose of the application layer?

To provide network services and functionality

What is the protocol used to access a secure website?

HTTPS

What is the TCP port number used by HTTPS?

443

What is the term used to refer to data at different layers of the OSI model?

Protocol Data Unit (PDU)

What is the correct order of the OSI layers from bottom to top?

Physical, Datalink, Network, Transport, Session, Presentation, Application

What type of addresses are used to make forwarding decisions at the data link layer?

Physical MAC Addresses

What is the memory aid used to remember the OSI layers from top to bottom?

All People Seem To Need Data Processing

What is the primary function of the transport layer?

Data segmentation and reassembly

What is the term used to refer to data at the network layer?

Packets or Datagrams

What type of connections are used in the transport layer?

Both Connection-oriented and Connectionless

What is the purpose of the memory aid 'Please Do Not Throw Sausage Pizza Away'?

To remember the OSI layers from bottom to top

What is the protocol used for reliable connections at the transport layer?

TCP (Transmission Control Protocol)

What is the term used to refer to data at the physical layer?

Bits

What is the device that lives at the data link layer and makes forwarding decisions based on MAC addresses?

Ethernet Switch

What is the term used to refer to data at the transport layer?

Segments

What is the protocol used for unreliable connections at the transport layer?

UDP (User Datagram Protocol)

What is the memory aid used to remember the protocol data units (PDUs) for the first four layers of the OSI model?

Bacon Frying Produces Salivation

Study Notes

OSI Model Overview

The OSI model is a reference model that helps understand how devices and protocols interact with each other in a network.
It has seven layers, each with specific jobs, but it's not a strict categorization model.

Physical Layer (Layer 1)

Concerned with getting bits on the wire (ones and zeros).
Uses physical media like cabling (e.g., fiber optic cables) to transmit data.
Data is referred to as bits at this layer.

Data Link Layer (Layer 2)

Makes decisions based on MAC addresses in an Ethernet network.
Examples of devices that live at this layer are Ethernet switches.
Data is referred to as frames at this layer.

Network Layer (Layer 3)

Concerned with logical IP addresses and making forwarding decisions.
Routers are typical devices that live at this layer.
Data is referred to as packets or datagrams at this layer.

Transport Layer (Layer 4)

Concerned with network connections and reliable/unreliable data transfer.
Examples of protocols that live at this layer are TCP (connection-oriented) and UDP (connectionless).
Data is referred to as segments at this layer.

Session Layer (Layer 5)

Concerned with setting up, maintaining, and tearing down sessions.
Examples of protocols that live at this layer are SIP (Session Initiation Protocol).

Presentation Layer (Layer 6)

Concerned with data formatting and presentation (e.g., JPEG, PNG, ASCII).

Application Layer (Layer 7)

Concerned with network functionality and applications (e.g., HTTP, HTTPS).
Examples of devices that live at this layer are web browsers and servers.

OSI Model Mnemonics

To remember the OSI model layers from bottom up: Please Do Not Throw Sausage Pizza Away Again.
To remember the OSI model layers from top down: All People Seem To Need Data Processing Again.

Learn how to analyze network components and their interactions using a reference model. This quiz helps IT professionals understand how devices and protocols work together.

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