The OSI Model

Question 1

What does the OSI Model represent?

Answer 1

It explains network communications between a host and a remote device over a LAN or WAN (Wide Area Network)

Question 2

Please  
Do        
Not     
Throw  
Sausage
Pizza
Away

Answer 2

An acronym for the OSI Model. Its represented in Bottom to Top.

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

Question 3

Layer 1, the Physical Layer?

Answer 3

Its the physical network cables and radio waves used to carry data over the network.

Note: Data at the physical layer is known as bits. It can be an electrical signal or radio wave.

Question 4

Layer 2, Data Link Layer

Answer 4

Describes how a connection is established, maintained, and transferred over the physical layer and uses physical addressing. (MAC Addresses (Media Access Control)). At this layer, Bits are grouped into Frames.

Note: Switches use MAC addresses as their form of physical addressing.

Question 5

Layer 3, Network Layer

Answer 5

Uses logical address to route or switch information between hosts, the network, and the internetworks. At this layer, Frames are grouped into Packets

Note: Switches and Routers can use IP addresses in addition to MAC addresses to route packets.

Question 6

Layer 4, Transport Layer

Answer 6

Manages and ensures transmission of the packets occurs from a host to a destination using TCP or UDP.

Note: TCP uses three way handshake. UDP uses fire and forget.
Note: TCP packages into Segments
Note: UDP packages into Datagrams

Question 7

Layer 5, Session Layer

Answer 7

This layer manages the establishment, termination, and synchronization of a session over the network.

Question 8

Layer 6, Presentation Layer

Answer 8

Translates the information into a format that the sender and receiver both understand.

Note: This is where formats like ascii and jpeg for example, are translated so the end user can use it.

Question 9

Layer 7, Application Layer

Answer 9

Layer from which the message is created, formed, and originated. This is talking about high-level protocols such as HTTP, SMTP, and FTP. Not things like MS Word or Powerpoint etc.