Computer Networks

Question 1

What is a computer network?

Answer 1

A connected network of computers (or printers, phones and other devices)

Question 2

Why do we have computer networks?

Answer 2

To share data (documents, images, videos and so on)

Question 3

How are devices connected in a computer network?

Answer 3

Wires or waves

Question 4

Name three types of networks.

Answer 4

LAN (or WLAN) -Local
MAN - Metropolitan
WAN - Wide

Question 5

WLAN

Answer 5

Wireless Local Area Network

Question 6

MAN

Answer 6

Metropolitan Area Network - eg between universities or hospitals in a large city

Question 7

WAN

Answer 7

Wide Area Network - Spans more than 30 miles, made up of multiple MANs. The Internet is the most known WAN.

Question 8

Parts of a network

Answer 8

Nodes - the connected devices
Communications media - How data is transferred (wires or waves)

Question 9

What is a server?

Answer 9

A special computer accessible to many users.

Question 10

What is a webserver?

Answer 10

Webservers are special servers accessible to anyone (with an internet connection), very powerful, a lot of memory.

Question 11

What is a request?

Answer 11

A message sent to a webserver requesting something (files)

Question 12

What is a client?

Answer 12

A device used to access the Internet. Recives file or data from server.

Question 13

What is a host?

Answer 13

The server, sends the file or data to the client.

Question 14

What component is needed in a computer to access the internet?

Answer 14

NIC - Network Interface Card

Question 15

What is a protocol?

Answer 15

A set of rules governing communication - format and order.

Question 16

What three parts are in this URL:

http://www.website.com/file.html

Answer 16

http:// - protocol
www.website.com - server name
/file.html - file

Question 17

What is network topology?

Answer 17

It describes different ways to lay out a network.

Question 18

Name 4 network topologies.

Answer 18

Bus
Ring
Star
Mesh

Question 19

What defines a bus network?

Answer 19

1 main cable and a terminator at each end to absorb signal. Cheap but breaks easily.

Question 20

What defines a ring network?

Answer 20

Each node connected to the next. Data hits each node until it reaches its destination. More common to use two rings with inverse data flow.

Question 21

What defines a star network?

Answer 21

All nodes connected to central node (router). Easy to expand, most common(?) like a WLAN. If central node breaks it all breaks.

Question 22

What defines mesh network?

Answer 22

All nodes connected to all nodes. Built in protection, data always has alternate routes. Very expensive, lots of communications media.

Question 23

What layers are in the OSI - model?

Answer 23

1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Data link
7. Physical

Question 24

OSI - model

Answer 24

Open Systems Interconnection - model

Question 25

Application layer?

Answer 25

The software that the user is looking at

Question 26

Presentation layer?

Answer 26

OS, letters and numbers (what we can understand)

Question 27

Session layer?

Answer 27

Conversation between two computers (getting data from a web server for example)

Question 28

Transport layer?

Answer 28

A packet is a chunk of data, packets are delivered reliably, in the proper order and according to how the protocol needs it

Question 29

Network layer?

Answer 29

Determines best route for data (routers are involved on this layer)

Question 30

Data link layer?

Answer 30

NIC's/checking for errors in data

Question 31

Physical layer?

Answer 31

Cable/fiber optics - any electric signals involved

Question 32

What does a modem do?

Answer 32

Connects your network to internet service provider.

Question 33

What 3 things does a router do?

Answer 33

- Connects via ethernet cable to modem. - Decides the route that the data is going to take. - Join networks together, your network with the internet for example.

Question 34

What does a switch do in a router?

Answer 34

Give more ports in router for devices. Can be managed / unmanaged. Managed switch gives more settings and control.

Question 35

What does a repeater do?

Answer 35

Boost a weak network signal. Not only for WiFi. 100m is max for ethernet cable, use wired repeater. Switches also work as repeaters.

Question 36

What two parts are in a IP address?

Answer 36

Network id, Host id

Question 37

What decides what part of an IP address is host / network?

Answer 37

Subnet mask

Question 38

What two problems are solved by subnet mask?

Answer 38

Networks can be different sizes No ip addresses are wasted

Question 39

DHCP

Answer 39

Dynamic Host Configuration Protocol

Question 40

What does DHCP do?

Answer 40

Assigns IP adresses in a network to connected devices.

Question 41

What does a device do when first connecting to a network?

Answer 41

Send out 'discover message' from default IP 0.0.0.0

Question 42

What happens when the router hears a 'discover message'?

Answer 42

Router looks through all IP adresses available in the network. Offers the first available to the new device - the computer requests it - router sends "Ack".

Question 43

DNS

Answer 43

Domain name system

Question 44

What does the DNS do?

Answer 44

Translate domain names like www.google.com to IP addresses - and back.