The OSI Model

Question 1

mnemonic to remember the 7 layers of OSI model

Answer 1

All - Application (7)
People - Presentation (6)
Seem - Session (5)
To - Transport (4)
Need - Network (3)
Data - Data Link Layer (2)
Processing - Physical (1)

Question 2

How the layers work together

Answer 2

• When information is passed down the OSI layers, each layer encapsulates the information with its own formatting and passes it to the next-lower layer
• eventually, the information is transmitted as bits at the Physical layer
• When information is passed up the OSI layers, each layer removes its formatting, or de-encapsulates the information, and organizes the information so that it can be interpreted by the next-higher layer
• The protocol data unit (PDU), or what the information is called at each layer, changes as it moves through the layers.

Question 3

PDU

Answer 3

protocol data unit

Question 4

Application Layer (7)

Answer 4

• Delivers appropriately formatted payload to the correct instance of an application.
• Includes protocols such as HTTP, SMTP and DNS
• manage communication between applications and then direct data to the correct program

Question 5

Presentation Layer (6)

Answer 5

• Converts data into different formats
• Includes formats such as MP3, JPEG, and GIF
• Data Format/Compression and encryption are often handled by the Presentation layer

Question 6

Session Layer (5)

Answer 6

• Data traverses the Session layer
• Establishes, Terminates and maintains communications
• Includes protocols such as Password Authentication Protocol PAP and Remote Procedure Call RPC.

Question 7

Transport Layer (4)

Answer 7

• Segments travers the Transport Layer
• Applies flow control and error detection
• Protocols TCP/UDP
• Responsible for the error-free delivery of information between devices

Question 8

Network Layer (3)

Answer 8

• Packets traverse the Network Layer
• Includes devices such as routers
• Protocols include IPv4, IPv6 and IPX

Question 9

Data Link Layer (2)

Answer 9

• Frames traverse the Data Link layer
• the Data Link layer includes devices such as switches
• Protocols include Ethernet, Frame Relay, Token ring, PPP, CDP
• Defines how devices communicate over a network and is responsible for managing physical addressing and switching on a network

Question 10

Physical Layer (1)

Answer 10

• Bits traverse the Physical layer
• Defines the physical characteristics and transmission of media.
• Includes devices like NIC’s, hubs, repeaters