Networks

Question 1

Define serial transmission

Answer 1

Data is sent one bit at a time down a single wire

Question 2

Define parallel transmission

Answer 2

Data is sent multiple bits at a time down several wires

Question 3

Define bandwidth

Answer 3

A measure of the capacity of the channel down which the data is being sent. It’s measured in hertz (Hz)

Question 4

State what is meant by bit rate

Answer 4

The rate at which data is actually being transmitted. Measured in bits per second

Question 5

What is latency?

Answer 5

The time delay that occurs when transmitting data between devices

Question 6

State what is meant by asynchronous data transmission

Answer 6

Data being transmitted between two devices that do not share a common clock signal

Question 7

State what is meant by synchronous data transmission

Answer 7

Data is transmitted where the pulse of the clock of the sending device and receiving device are in time with each other. The devices may share a common clock.

Question 8

What are protocols? Give some examples of protocols used in networks

Answer 8

Protocols are a set of rule.
TCP/IP are a set of protocols for all TCP/IP network transmissions.
HTTP (HyperText Transfer Protocol) are a set of rules to define the identification, request and transfer of multimedia content over the internet.
FTP is a set of rule for handling file uploads and downloads.

Question 9

What is a network?

Answer 9

Devices that are connected together to share data and resources

Question 10

state what a network interface card (NIC) is

Answer 10

A card that enables devices to connect to a network

Question 11

What is meant by LAN and WAN?

Answer 11

LAN (Local Area Network) is a network over a small geographical area - usually one site and typically used by one organisation.
WAN (Wide Area Network) A network spread over a large geographical area.

Question 12

Define what a network topology is and give some examples

Answer 12

A network topology is usually in terms of conceptual layout of a network rather than the physical one.
Two example of network typologies are bus and star.

Question 13

What is the bus network typologies and state some advantages and disadvantages

Answer 13

Bus - A network layout that uses one main data cable as the backbone to transmit data. Advantages : Cheaper and easier to install than a star topology and easy to add new devices to the network.
Disadvantages: less secure than a star topology, Slow transmission times one larger bus networks, if the main cable fails then all networks are affected, Less reliable than a star topology due to the reliance on one cable, Difficult to fault find.

Question 14

What is the star network typologies and state some advantages and disadvantages

Answer 14

Star When each device on the network is connected to a central computer or switch via it’s own cable. disadvantages : more expensive and harder to install than a bus topology and harder to add new devices to the network, if a cable fails that client may not be able to receive data.
Advantages: more secure than a bus topology, little slow down on large networks, If one cable fails then only one client is affected, fault finding is easier than on a bus network.

Question 15

Define what is meant by client-server

Answer 15

A network methodology where one computer has the main processing power and storage and the other devices on the network act as client and request services from the server.

Question 16

Define what is meant by a Peer-to-peer network

Answer 16

A network methodology where all devices in a network share resources between then rather than having a server.

Question 17

Define what a WWAN is

Answer 17

A WAN that doesn’t use cables but send data wirelessly

Question 18

What is a MAC address?

Answer 18

Media Access Control address is a unique code that identifies a particular device on a network

Question 19

What is WIFI?

Answer 19

A standard method for connecting deices wirelessly to a network and to the network and to the internet

Question 20

Define what a WLAN is

Answer 20

A LAN that doesn’t use cables but send data wirelessly

Question 21

What is SSID?

Answer 21

Service Set Identifier - A unique 32-character code that identifies a device on a wireless network. Used to make sure the devices on a wireless network are connecting to the right WLAN.

Question 22

What is the RTS/CTS protocol?

Answer 22

Request to send /clear to send - A protocol to ensure data doesn’t collide when being transmitted on a wireless network. The device wishing to send data sends the RTS signal and waits for the CTS signal, if it receives the CTS signal it knows the receiving end is idle. If no CTS signal is received it the sender waits a random amount of time and then re-sends the RTS signal.

Question 23

How do you improve security on a wireless network?

Answer 23

• Change the SSID from the default and hide it from transmission.
  
  • Ensure all devices are WPA/WPA2 compliant.
  • Use strong encryption (WPA/WPA2).
  • Create a white list of MAC addresses from the devices you want to access the network.

Question 24

What is WPA/WPA2?

Answer 24

WIFI Protected Access (WPA/WPA2) is a protocol for encrypting data and ensuring security on WIFI networks

Question 25

What is the internet?

Answer 25

A global network of networks. It started life as ARPANET in the late 1960’s. The internet as we know it was created in the mid 1980’s when a British scientist created the World Wide Web (WWW).

Question 26

Define URL

Answer 26

Uniform Resource Locator (URL) - A method for identifying the location of resources (e.g. websites) on the internet.

Question 27

When HTTP is included with a URL what does it indicate?

Answer 27

When HTTP is used as part of a web address it indicates that the file can be accessed using a browser. Most URLs start with HTTP, although it’s not necessary to type it into the address line.

Question 28

Define domain name

Answer 28

Domain name is the recognizable name of a domain on the internet.

Question 29

What is an IP address?

Answer 29

Internet Protocol address (IP address) is a unique dotted quad number that identifies devices on a network. These numbers make little sense to people so instead we use domain names to represent the IP address.

Question 30

What is used to go from a domain name to an IP address?

Answer 30

To convert a domain name to an IP address, so the data transmitting protocols can be used, we use a domain name server. This is a server that contains domain names and associated IP address.

Question 31

What is a non-routable/private IP address?

Answer 31

This is an IP address used on a private network (e.g. a home or school). Despite the IP address being needed in order to route around a network this address doesn’t need to be made public as the device isn’t directly connected to the internet as it can be hidden behind a firewall or router.

Question 32

Define port

Answer 32

A port is used to identify a particular process or application on a network. Such as POP3 which is a protocol used for receiving emails. Port addresses are often used for processes that are common in networking task and many have been assigned port numbers that are in wide spread use. There are around 250 common ports.

Question 33

What is SSH?

Answer 33

Secure Shell (SSH) Protocol is a protocol for remote access to computers.

Question 34

How do you match up private IP addresses with public ones?

Answer 34

A process called Network Address Translation (NAT). Using this has 2 main advantages;

1) A unique IP address isn’t needed for every device on a network, only the router or server that is physical needs one
2) There is an increased level of security as the private IP address isn’t being broadcast over the internet

Question 35

What name is given to the system of connected DNS that provides the IP addresses of every website on the internet?

Answer 35

Domain name server (DNS) system

Question 36

How does NAT work?

Answer 36

The router maps all the private IP addresses to a port number and the corresponding public IP address. The workstation trying to access the internet will send a packet containing the data it wants to send, its own internal IP and the port number that it generates. The router then logs the internal IP address and the port number and replaces them with its external IP address. When data is sent back to the router it looks at the port address it was sent back to and looks it up in the table that it saves the internal IP addresses and corresponding port numbers to and sends the data the the relevant internal IP address. Id the table doesn’t contain a matching port number the packet is dropped.