Intro to Networking

Question 1

What is a LAN, MAN and a WAN?

Answer 1

LAN - Local Area Network, a network of interconnected devices in a limited geographic area.
MAN - Metro Area Network, a network that spans a few buildings in a slightly bigger area than a LAN.
WAN - Wide Area Network uses 3rd party communication providers to carry network traffic from one place to another.

Question 2

What is an Internetwork, Internet and Intranet?

Answer 2

Internetwork - A collection of LANS tied together by devices such as routers.
Internet - Worldwide Public internetwork that uses TCP/IP and HTTP.
Intranet - A private internetwork in which devices and services are only available to specified users (eg employees at a company).

Question 3

What is the smallest increment of data on a computer?

Answer 3

A bit

Question 4

What is a packet?

Answer 4

A chunk of data with a source and destination IP address added. Usually uses some form of TCP/IP

Question 5

What is a frame?

Answer 5

A packet with the source and destination MAC addresses added.

Question 6

Why are packets used for data transfer?

Answer 6

• Pauses between packet transfers allow other PCs to transfer data
• Allows receiving computer to process and error check data.
• If an error occurs only the affected packet needs to be re-sent.
• Gives the sending computer a chance to receive data from other computers and perform other processing tasks.

Question 7

What are the 3 hardware components of network communication?

Answer 7

Network Interface Card (NIC)
Network medium
Interconnecting device

Question 8

What is an NIC and what does it do?

Answer 8

Network Interface Card provides a connection between a computer’s motherboard and the network.

Question 9

Give two examples of a network medium.

Answer 9

Ethernet cable

Wireless

Question 10

What are routers, hubs, switchers and access points used for?

Answer 10

Routers - used for connecting multiple networks together
Hubs - Connect computers on a network together.
Switches - Used for connecting multiple computers within a network and can read data destinations.
Access points - Allow computers to connect to a network wirelessly.

Question 11

What is the most common network architecture model?

Answer 11

Star Topology

Question 12

What is the con of using a Star Topology?

Answer 12

If the central access point fails the whole system goes down.

Question 13

What are the steps of network communication?

Answer 13

1. App tries to access network resource by sending a message.
2. Client software formats message and passes it to network protocol.
3. Protocol packages the message in a network suitable format and sends it to NIC driver.
4. NIC driver sends data in request to NIC card to be converted into necessary signals to be transmitted over network.

Question 14

How is encapsulation used in network communication?

Answer 14

Data is encapsulated into packets then frames. As data is moved through each layer of the sending computer different headers and tailers are added to it so it ends up being a multi-layered package with data at it’s center. The receiving computer gets the package and as it moves through each layer decapsulates it until it can receive the data in the center.

Question 15

What is the purpose of OSI?

Answer 15

Describes the functions of a baseline network system while remaining protocol agnostic.

Question 16

For layer 7
Name:
Purpose:
Protocols:
Common errors:

Answer 16

Name: App Layer
Purpose: Provides interfaces for apps to access network services.
Protocols: HTTP, FTP, SMTP
Common errors: Misconfigured client or server software or incompatible commands.

Question 17

For layer 6
Name:
Purpose:
Protocols:
Common errors:

Answer 17

Name: Presentation Layer
Purpose: Handles data formatting and translation.
Protocols: N/A
Common errors: Encryption or decryption errors.

Question 18

For layer 5
Name:
Purpose:
Protocols:
Common errors:

Answer 18

Name: Session
Purpose: Allows to computers to hold ongoing communication.
Protocols: Name lookups, User logon and logoff.
Common errors: User login errors.

Question 19

For layer 4
Name:
Purpose:
Protocols:
Common errors:

Answer 19

Name: Transport layer
Purpose: Manages data by breaking it down into segments to ensure it is under maximum frame size.
Protocols: N/A
Common errors: N/A

Question 20

For layer 3
Name:
Purpose:
Protocols:
Common errors:

Answer 20

Name: Network Layer
Purpose: Performs logical addressing and maps IP into physical addresses. Also performs routing by selecting the best path.
Protocols: IP, ARP, ICMP
Common errors: Router error and IP masking errors.

Question 21

For layer 2
Name:
Purpose:
Protocols:
Common errors:

Answer 21

Name: Data Link
Purpose: Works with frames and is intermediary between network and physical layer. Frame check sequences (FCS) are added here.
Protocols: N/A
Common errors: Collisions and invalid frames.

Question 22

For layer 1
Name:
Purpose:
Protocols:
Common errors:

Answer 22

Name: Physical Layer
Purpose: Converts bits into signals for outgoing or signals to bits for incoming messages.
Protocols: Wire media uses elec pulses, Fibre optics uses light pulses and wireless uses radio waves.
Common errors: EC interference, malfunctioning hardware or multiple signals over same channel.

Question 23

What is a pro of network layering?

Answer 23

Helps troubleshooting.

Allows for segmentation of control, updating and testing.

Question 24

What is a packet sniffer?

Answer 24

Software that can intercept and log data passing over a network.

Question 25

Why can’t we use straight-through cables for everything?

Answer 25

Network cables have 8 pins. Computers send on pins 1,2 and receive on pins 3,6, therefore if we connect them together using a straight though cable the send pins would be connected together and the receive pins would be connected together meaning no messages could get through. We would need to use crossover cables which have send pins 1 and 2 connected to receive pins 3,6 and the second device.

Question 26

What is auto-MDIX and why is it useful?

Answer 26

Auto-MDIX allows devices to auto detect which cable type is needed between connections and switch the send receive pins automatically meaning we don’t have to work out which cable to use.