OSI Layers

Question 1

How many layers are in the OSI Model?

Answer 1

7 Layers

Question 2

What are the seven layers of the OSI Model?

Answer 2

Physical, Data-link, Network, Transport, Session, Presentation, Application (Please Do Not Throw Sausage Pizza Away)

Question 3

What defines the OSI Model layers?

Answer 3

ISO 7498

Question 4

Why do people refer to a Network stack?

Answer 4

The layers either operate from the top down, or the bottom up.

Question 5

What is Layer 1 (of the OSI model) and what is it responsible for?

Answer 5

The Physical Layer. It transmits logical bits over physical current (1’s and 0’s). Even a wireless system is considered physical as far as the network stack is concerned.
* could be transmitted as electrical impulses across a copper wire, waves over an RF signal, or light over a fiber optic.

Question 6

What are some devices that work at Layer 1 (Physical Layer)?

Answer 6

NICs (Network Interface Card), Repeaters and concentrators.

Question 7

Which Layer in the OSI Model is called the MAC Layer?

Answer 7

Layer 2: Data-link.

Question 8

What Layer does physical addressing occur?

Answer 8

Layer 2: Data Link

• MAC Layer
• Link Layer
• Deals with a unique address per device that is used for collision detection, error detection
• Deals with the reliable transfer of data.

Question 9

In the Data-Link Layer (Layer 2), what does the link-layer (LLC) focus on?

Answer 9

governs sequence numbers and acknowledgements.

Question 10

In the Data-Link Layer (Layer 2), what does the MAC deal with?

Answer 10

(Media Access Control) MAC governs data transfer and collision handling.

Question 11

What are some devices that are associated with the Data-link Layer (Layer 2)?

Answer 11

ATM (asynchronous transfer mode), switches, bridges.

Question 12

What Level does Logical Addressing occur?

Answer 12

Network Layer (Layer 3)

Question 13

What level does Internet Protocol (IP) reside?

Answer 13

Network Layer (Layer 3)

Question 14

Where does routing of packages occur? (From 1 point to another)

Answer 14

Network Layer (Layer 3)

Question 15

At the Network Layer (Layer 3) what is a fragment of data called?

Answer 15

A packet

Question 16

At the Data-link Layer (Layer 2) what is a fragment of data called?

Answer 16

A Frame

Question 17

At the physical layer (Layer 1) what is a fragment of data called?

Answer 17

A bit

Question 18

What are some devices you would find at the Network Layer (Layer 3)?

Answer 18

Bridges and routers

Question 19

What are some protocols found on the Network Layer (Layer 3)?

Answer 19

IP, ICMP, IPSec

Question 20

What layer deals with ensuring the delivery of information, and the control of the flow of information?

Answer 20

Transport Layer (Layer 4) . End to end connection reliability.

Question 21

What protocols are associated with the Transport Layer (Layer 4)?

Answer 21

TCP (Transport Control Protocol), UDP.

Question 22

Which layer is responsible for Inter-host or inter-application communication.

Answer 22

Session Layer (Layer 5)

Question 23

What are some protocols associated with the Session Layer (Layer 5)?

Answer 23

RTCP, PPTP, RPC

Question 24

What layer deals with compatibility between desperate systems, and data formatting. The layer that does the final steps to get the data in the proper format prior to delivering to the application.

Answer 24

Presentation Layer (Layer 6)

Question 25

What layer does the Client software communicates with the network stack.

Answer 25

Application Layer (Layer 7)

Question 26

What protocols are associated with the Application layer.

Answer 26

DNS, FTP, SSH, HTTP