Network Model

Question 1

What is the OSI model and what does each layer do (examples help)? Remember to number the layers, as that’s how it’s referenced.

Answer 1

OSI Model:

7. Application – API of an application (how we make it network aware)
8. Presentation – If data comes in, can your computer read it? Used to convert data to readable data
9. Session – What’s taking place and how that connectivity works
10. Transport – Disassemble packets
11. Network – Logical addresses, IP Address (routers)
12. Data Link – Anything that uses Mac Address (Network card and switches)
13. Physical - Hardware

Question 2

What is the TCIP Model? Include explanation of each layer and the number.

Answer 2

TCIP Model

4. Application – Email, FTP, Tellnet
5. Transport – What it takes to get the data to the other location.
6. Internet – routers
7. Network Interface – hardware except for routers

Question 3

What is the process for receiving data and what layers does it include?

Answer 3

PHYSICAL AND DATA/LINK and NETWORK INTERFACE LAYER:
Network Card verifies that the data is for the user (verifies via Mac Address)
Data link checks that it is good data. It deciphers it by removing the Mac addresses, and what you have is an IP PACKET.

Question 4

What does the transport layers do?

Answer 4

TRANSPORT AND TRANSPORT LAYER:

It assembles or disassembles based on sequencing numbers.

Question 5

What does the session layer do?

Answer 5

Connect a server to an application. Most modern applications do this automatically (Outlook starting and connecting to exchange), but it used to be a manual process before

Question 6

What’s the presentation layer do?

Answer 6

ASCII Files and making sure its readable

Question 7

What’s the process for sending data? Include layers and explanation of what they do.

Answer 7

SENDING DATA PROCESS -
Application, Presentation, Session: gather data, source, and to port numbers.

Transport: Organizing data into IP packets with sequencing numbers

Network: Adds Ip address to the TCP Segment

Data Link: Adds Mac Address to the IP Packet

Physical: Verify the integrity and sends it out to the destination.

Question 8

How many bits is a MAC address?

Answer 8

48 bit address because it’s in hexadecimal and there’s 12 numbers. 1 Hexadecimal = 4 digits. 4 x 12 = 48 digits

Question 9

What is a MAC address? Which part is the OEM identifier (what is it) and which is the unique ID?

Answer 9

Mac Address is 12 numbers broken up in pairs of two
The first 6 digits is called the OEM Identifier
The last 6 digits is called the unique ID

Question 10

What’s the difference between unicast and multicast?

Answer 10

Unicast transmission is meant for one device on the network. The computer can tell this when it sees the packet is intended for it’s specific Mac address
Broadcast comes in repeating Fs: FF-FF-FF-FF-FF-FF
When a PC sees that it is a Broadcast Mac Address, it will process the data regardless because it’s in a Broadcast domain.

Question 11

What’s a broadcast domain?

Answer 11

Broadcast domain – It’s basically a LAN. It’s interconnecting PCs on a LAN. A broadcast transmission is sent to every device in a broadcast domain

Question 12

What is the range of port numbers on a router? Which are reserved?

Answer 12

Range of port numbers go from 0-65535.

First 1024 are reserved

Question 13

What port is normally reserved for HTTP connections?

Answer 13

Port 80

Question 14

Which port is normally reserved for FTP connections?

Answer 14

Port 20/21