1.1 Network Fundamentals OSI MODEL

Question 1

What does the OSI Model Mean and its Purpose?

Answer 1

OSI Model means Open System Interconnect. It is a guidline to describe the way data moves across the network.

Question 2

How many Layers are in the OSI Model and Name them all

Answer 2

7 Layers in the OSI Model
1.Physical
2.Data Link
3.Network
4.Transport
5.Session
6.Presentation
7.Application

Question 3

What is Layer 1 in the OSI Model and what does it consist of?

Answer 3

Layer 1 is the Physical Layer
Consist of the Physcial Structure of the Computer such as.
Coax,Fiber Optics,Wireless Devices, Hubs, repeaters

Question 4

What is Layer 2 in the OSI Model and what does it consist of?

Answer 4

Layer 2 is the Data Link Layer
inspects incoming frames to see if they are addressed for this desintination based on the MAC address

consist of two sub-Layers

Logical Link Controller(LLC)- provides the logic for the data link. thus controls the synchronization, flow control, and error checking functions of the data link layer.

Media Access Control(MAC)- this sublayer provides control for accessing the transmission medium. It is responsible for moving data packets from one network interface card (NIC) to another, across a shared transmission medium.

Question 5

What is Layer 3 in the OSI Model and what does it consist of?

Answer 5

Layer 3 is the Network Layer
looks at the incoming packet ip addresses and ensures its going to the correct destination.

Used ip addresses for large distributed networks like the internet which is better then mac address which is only good for local LAN

Has 2 Main Functions.
1. to break down segments into packets and reassembling the packets into the receiving end(Fragmentation)
2.routing packets by discovering the best path on the physical network.

ICMP,IGMP,IP,Ipsec

Question 6

What is Layer 4 in the OSI Model and what does it consist of?

Answer 6

Layer 4 is the Transportation Layer
known as the POST office Layer
describes how data is being delivered and how it is delvered using 2 protocols
TCP & UDP

Question 7

What is Layer 5 in the OSI Model and what does it consist of?

Answer 7

Layer 5 is the Session Layer
The session layer creates communication channels, called sessions, between devices.
It is responsible for opening sessions, maintaining Sessions by ensuring they remain open and functional while data is being transferred, and terminating Session communication ends between end users.

The session layer can also set checkpoints during a data transfer—if the session is interrupted, devices can resume data transfer from the last checkpoint

Question 8

What is Layer 6 in the OSI Model and what does it consist of?

Answer 8

Layer 6 is the Presentation layer
The Presentation Layer defines how two devices shall receive data by encrypting, decrypting , compress or decompress in order for it to be presentable to the receiving end.

Question 9

What is Layer 7 in the OSI Model and what does it consist of

Answer 9

Layer 7 is the Application Layer
Application layer is the upper most layer of the OSI Model Application layer protocols allow the software to direct data flow and present it to the user.

Some of the known protocols include Hypertext Transfer Protocol (HTTP), Simple Mail Transfer Protocol (SMTP), and File Transfer Protocol (FTP).