3 - Computer networks, connections and protocols"

Describe the difference between a LAN and WAN. [2]

-A WAN uses third party cabling to transfer data between terminals across the network - WAN's cover a large geographical area. -A LAN uses proprietary cabling owned by the company using the network. LAN's are typically spread over a smaller geographical area

Describe what is meant by a LAN. (2)

Local Area network (Over) a small geographical area Use of hard-wiring / wireless communication

State two advantages of having a LAN instead of a set of stand-alone machines. (2)

Communication between machines / workers Any machine can be used Easier to maintain / add / delete software / files Sharing of peripheral devices / software / data Monitoring of workers Simplifies backup procedures

Explain two factors that can affect network performance. (2)

- Bandwidth: the amount of data that can be transferred at one time. - Latency: the speed that data travels during transfer (or delay in receiving). - Error rate: the number of collisions in high network traffic. - Retransmission rate: how promptly corrupted or last packets can be resent.

State two types of network transmission media. (2)

- Copper cable (twisted pair Ethernet cable) - Fibre optic cable - Wireless (WiFi) signals.

What is a Network interface card (NIC)? (2)

Internal hardware that allows a device to connect to a network. It used to be a separate card but nowadays is built into the motherboard

What is a Switch? (2)

- Hardware that connects devices on a LAN.

- They receive data through frames from one device and transmit it to other devices on the network with the correct MAC address

What is a Router? (2)

- Transmits data between networks. - It's directs packets on the internet and are used to connect a LAN to the internet

Describe one piece of hardware that each shop will need to connect their LAN to the company's WAN. [2]

What are the advantages of a LAN? (6)

Sharing files is easier. Easily work collaboratively. Share same hardware. Install software all at once. Communication - cheap Login from any device

Give 5 factors that affect the performance of a network... (5)

-Bandwidth - amount of data transferred in a given time

-Number of devices/ Heavy use - can cause congestion

-Interference - physical obstruction + range of device

-Wired/ Wireless - more faster/ reliable than wireless

-Hardware/ Topologies - cables

What are the disadvantages of a LAN? (4)

- Purchasing the network cabling and file servers can be expensive.

- Managing a large network is complicated, requires training

- If the file server breaks down the files on the file server become inaccessible.

- Viruses can spread to other computers throughout a computer network.

What is Latency? (2)

Latency is the technical word for 'delay' - how long it takes for a packet to reach its destination. The larger the network, then the longer it takes for a bit to travel from one point to another.

What is an error rate? (2)

An error happens when a binary 1 was sent, but a binary 0 was actually received, or the vice versa. There are two main reasons for errors happening: interference and weak signal.

Explain the differences between a client and a server in a client-server network (4)

A client is a device or application that requests services or resources from a server, while a server is a system that provides those services or resources to clients. Clients typically initiate communication, whereas servers wait for requests to process and respond,

Give two advantages of using a client-server network model. (2)

- Central storage of files so users can access them from any computer.

- All client computers can search/update a central database to avoid multiple copies being out of sync.

- Backups can be made centrally so that individuals do not need to backup their own client machines.

- Security can be managed centrally using antivirus software on the server.

Give two disadvantages of using a client-server network model. (2)

- Requires a costly maintenance team to manage the network and the server.

- Too many client requests degrades server performance.

- If the server or its network connection go down, the service is lost for the whole network.

Give two advantages of using a peer-to-peer network model. (2)

- Easier to set up

- computers can simply be cabled together

- No need for dedicated server equipment

- Individual computers can share a printer, router, modem and other hardware

- Users can communicate directly with each other and share each other's files

Give two disadvantages of using a peer-to-peer network model. (2)

- Viruses and malware are more easily transferred over this type of network as there is no central firewall

- Data recovery and backup is not done centrally, so each computer has to have it own backup system

- more difficult to manage.

What are the hardware components required to connect stand-alone computers into a Local Area Network (LAN)? Describe the function of each component. (5)

The hardware components required to connect stand-alone computers into a Local Area Network (LAN) include a router, switches, network cables, wireless access points, and network interface cards. The router connects different networks and directs traffic, switches connect multiple devices within the same network, network cables facilitate communication, wireless access points enable wireless connectivity, and network interface cards allow computers to connect to the network.

Describe the purpose of the router in the house's network. (2)

Directs packets/data to destination // directs packets/data in a network Receives packets/data from the network/Internet Forwards packets/data to other computers on the network/Internet Connects (different) networks together // e.g. joins home network to Internet Has (public) IP address for LAN Designates (private) IP addresses to network nodes

Identify two additional items of network hardware, apart from cables and a router, that may be used within the house network. (2)

What are the advantages of the client-server model over the peer-to-peer model? (2)

-data can be backed up centrally rather than on each individual computer

-security is improved as data is held in one location rather than spread across the network

-users can log in to any computer on the network

Describe one scenario where a peer-to-peer network would be advantageous over a client-server network, and suggest why. (2)

Small business, online gaming groups or another other acceptable suggestions.

Reasons include - simpler set up

- no central network administration required

- no special software to manage the network.

Name three advantages of linking computers in a small office in a peer-to-peer network. (3)

- Individual computers can share hardware such as printer, scanner, router, modem

- Users can communicate directly with each other and share each other's files

- Easy and cheap to set up and no special software required

Briefly describe what is meant by 'The Cloud' (1)

Remote servers that host your data, resources and applications; via the Internet.

Give two advantages to using cloud-based services over local storage. (2)

- Data can be accessed from any computer in the world, not just your own local machine.

- Local storage on your hard disk is significantly reduced if software and files are stored remotely.

- Backing up is no longer crucial since cloud service providers will include this as part of their service.

Explain two advantages and two disadvantages of using cloud computing for businesses. (4)

Advantages - No need to upgrade software - Work is automatically saved/backed up - Collaboration can work - with multiple people working on the same document at once - Any connected computer can access services - Users don't need to buy/install software - cheap. Disadvantages - Completely reliant on the network/ internet - Sensitive company data may be stored in a different country which may not adhere to same data - protection regulations as their own (Security risk) - Lack of control - you can't do much if files or the server are hacked or a virus is installed, even if its your data

Explain how a DNS server is used to access a website given the address the user has entered (3)

-DNS servers use a database of website of their website addresses and their corresponding IP addresses

-a website address that is entered is looked up in a DNS database to find the matching IP address

-if it can't find the address, it searches on other DNS servers

Explain the advantages of using DNS servers. (2)

Advantages: - People do not need to remember IP addresses. - Easily upgradeable (eg IPv4 to IPv6) without all web addresses needing to be the same. - As long as you are connected to a DNS server you can have access to all the addresses.

A company produces digital photo frames (i.e. photo frames that display digital photographs). Several of these photo frames can be placed around a house and connected in a peer to peer network. Describe what is meant by the term 'peer to peer network'. (2)

A school decides to use the star topology to create the LAN. Describe what is meant by a star topology. You may use a diagram. (2)

A hub/server at the centre of the network.All computers attached to the hub/server. Resources (e.g. printer) can also be connected to the hub/server.

A classroom in a primary school has 6 standalone computers. The school decides to connect them to form a LAN in a star topology. Explain, with reasons, what additional hardware will be required to create this LAN. (2)

- The star topology requires all workstations to be connected to a central point so a hub/switch is needed. - The computers need to be physically or wirelessly connected to the hub so cables and NIC or a WAP and WiFi adapters will be needed.

State two advantage and one disadvantage of a mesh network over a star network (4)

advantage :

-mesh networks are self-healing/have no single point of failure

-data can be transmitted from different devices simultaneously

-require no additional hardware disadvantage

disadvantage:

-mesh networks can be expensive to install/often have redundant connections

-network maintenance and administration is more complicated than a star network

Describe what is meant by a mesh topology. (2)

Mesh topology - nodes are all interconnected and act as routers for data in order to relay and propagate data

State two advantage and one disadvantage of a star network over a mesh network (4)

advantage - Fast data transfer to the hub as each wire isn't shared with the other computers - If one cable fails the others aren't affected - Network management can be done centrally - Signals don't need to be transmitted to all devices in the network disadvantage - Requires additional hardware such as the central switch and network cables - If the central switch fails, whole network goes down.

Explain the difference between a wired and wireless connection. (2)

A wired connection uses physical cables to connect devices to a network, while a wireless connection uses radio waves to connect devices to a network.

Give two advantages and two disadvantages for Wired and Wireless connections. (4)

Advantages of a wired connection include: Higher reliability: Wired connections are less susceptible to interference and can provide a more stable connection than wireless connections. Higher speed: Wired connections can provide faster data transfer rates than wireless connections. Disadvantages of a wired connection include: Limited mobility: Devices connected to a wired network must be physically connected to the network, which limits their mobility. More difficult to set up: Setting up a wired network can be more complex than setting up a wireless network, as it requires physical cabling. Advantages of a wireless connection include: Greater mobility: Devices connected to a wireless network can move around freely within the range of the network. Easier to set up: Wireless networks are typically easier to set up than wired networks, as they do not require physical cabling. Disadvantages of a wireless connection include: Lower reliability: Wireless connections can be affected by interference from other wireless devices and obstacles such as walls. Slower speeds: Wireless connections typically provide slower data transfer rates than wired connections.

State two factors that may cause interference of the WiFI signal (2)

-physical objects e.g walls -other electronic devices -neighbouring networks using overlapping channels

What other services beside cloud-based software may be provided by Internet hosts? (1)

-website hosting -online file hosting -video hosting services

Explain the difference between Bluetooth and Wi-Fi technology. (2)

Bluetooth and Wi-Fi are both wireless communication technologies, but they differ in their purpose and functionality. Bluetooth is designed for short-range communication between devices, while Wi-Fi is designed for long-range communication between devices and networks.

What is meant by 'encryption' (1)

The encoding of data so that it can no longer be understood

What are the advantages of using Copper cables? (2)

- Tried and trusted technology - Relatively cheap

What are the disadvantages of using Copper cables? (3)

- Signal affected by electric and magnetic fields - Low bandwidth - Heavy cables

What are the advantages of using Fibre optics? (3)

- Very fast data transmission - Low loss of signal over distance - Not affected by magnetic and electric fields - require very little power - More difficult to tap into than copper cables

What are the disadvantages of using Fibre optics? (2)

- High investment cost - Need for expensive optical transmitters and receivers

What is the difference between IPv4 and IPv6 addresses? (2)

IPv4 - 4 blocks of denary digits between 0 and 255 Values separated by full stops. IPv6 - 8 blocks of 4 hexadecimal digits Values separated by colons.

What is the difference between an IP address and a MAC address? (2)

A MAC address is permanently assigned to a device on the network whereas an IP address may change when the device joins a different network.

What are three differences between Bluetooth and Wi-Fi? (3)

- Bluetooth uses less power - Bluetooth has a shorter range - Bluetooth has a slower data transfer speed - Bluetooth is normally used for ad-hoc connections - Bluetooth is normally used for personal devices/as part of a PAN, rather than a LAN

Explain what is meant by a 'protocol' (1)

a set of rules (-...to govern data transmission (between devices))

Data packets move up and down layers in a protocol stack as they are sent and received. What are the advantages of using 'layers' in this context? (2)

-each layer is self-contained, so can be edited without affecting other layers -developers can concentrate on one network area without knock-on effects

Explain why protocols are important on a network. (2)

- Allowing them to communicate - By ensuring all devices follow the same rules/standards - So they interpret data/signals in the same way

TCP/IP uses packet switching. Explain what is meant by packet switching. (4)

Data is split into chunks called packets which have labels including address being sent to and order. Each packet is sent on the most convenient / avoidable route meaning they may arrive in a different order to which they were sent. Once packets arrive at receiver they are reordered.

Explain how packet switching is used to send data across the Internet (5)

-the website data is broken down into small packets/chunks of data -each packet is numbered -given the sender's and recipient's IP address -and sent separately -packets are reassembled at the destination -and checked for errors -lost or corrupted packets are resent

Explain the various layers of a network. (4) DNTA

Data link layer and physical layer - provides physical transport of data through electrical signals. Network layer - provides routing of data across networks by making use of addressing. Transport layer - provides transport of data between devices by splitting files into data packets and checking that they have been sent and received properly. Application layer - provides user access to applications, websites, files and email.

Explain the reason for data packets (2)

data packets are required so that data can be sent across a network. Without splitting files into tiny data packets the file will need a dedicated channel between two computers and as nobody owns the internet there is no way of setting up such a channel so instead data packets are sent across millions of different available routes and combined to reform the file at the destination computer.

Describe fully the various components found in a data packet, explaining why they are needed (5)

data packets are made up of the following: data: without this, the packet would not carry any data destination address: without this, the packets would not be sent anywhere return address: without this, if a data packet was corrupted on the route a replacement packet could not be fetched sequence number: without this, the received packets could not be combined correctly to reform the original file error check number: without this, there would be no way of knowing if the received data packets had become computed on their journey

What is HTTP stand for and used for? (2)

- (HyperText Transfer Protocol) Used for accessing and receiving web pages via the internet. Requests a web page from a web server, which sends a response containing the web page, if found.

What is the difference between HTTP and HTTPs? (2)

HTTPs - secure HTTP which encrypts the information using asymmetric encryption so it cannot be read by an outsider.

What is hosting? (2)

-when websites are stored on servers dedicated for the purpose of converting web addresses to IP addresses -hosted solutions provide 24/7 access, multiple users and greater security

Give an advantage and disadvantage of ethernet. (2)

advantage - fast transfer speeds - better physical security - better range disadvantage - can't move easily - cables could be a trip hazard - need more cables to add a new device

Give an advantage and disadvantage for WiFi. (2)

advantage - easy to move around - most devices already have a wifi adapter - easy to add new devices disadvantage - data can be intercepted by anyone in range -obstructions weaken signal strength - slower transfer speeds

Give an advantage and disadvantage for bluetooth. (2)

advantage -very low power consumption -ideal for personal devices -easy to make ad-hoc connections disadvantage -data can be intercepted by anyone in range -very short range very slow transfer speeds

What is the purpose of an IP address? (1)

-used to uniquely identify a computer within that network

What is the purpose of an MAC address? (1)

- uniquely identify a device

What do standards do? (2)

provide rules (1) that make different manufacturers create products that work together (1), hardware and software

What is the FTP protocol and when should it be used? (2)

- File Transfer Protocol - is a protocol used to transfer (upload and download) data between a client and a server on a computer network. - a way to download, upload and transfer files over the internet - when you want to transfer files to different computers

Sophia and her brother Fergus both use webmail accounts to communicate via email. Describe what happens when Sophia sends an email to her brother (2)

-Sophia's email is written and sent to a local mail server -the mail server forwards this on Fergus' mail server via the Internet -Fergus logs into his email account and downloads the message from his local mail server

What protocol would be used to send the email to Fergus (1)

SMTP (simple mail transfer protocol)

State the difference between POP and IMAP protocols and how they affect the use of multiple devices to access the mail (3)

-POP (post office protocol) will download the entire message and delete it from the server -IMAP (Internet Message Access Protocol) will download the message header and leave the message on the server -IMAP will synchronise all devices with the server's mailbox

What does the TCP protocol do and stand for? (3)

The TCP (Transmission Control Protocol) Breaks up messages sent over the Internet into small chunks called packets, reassembles the packets at the other end, detects errors and resends lost messages

What does the IP protocol do and stand for? (2)

- Routes individual packets from one IP address to another - (Internet Protocol)

why is splitting data into small packets good? (3)

-individual packets can find the quickest/shortest route -if the network changes while the data is being sent, subsequent packets can find alternative routes -if a packet is lost, only that packet needs to be resent

What is a 'layer'? (1)

A division of network functionality

The computer that accesses the websites are called...

clients

Explain why the number of devices using the network at the same time can affect the performance of the network? [4]

Explain, why Ethernet is a standard? [2]

Identify three tasks carried out by the router. [3]

What is Ethernet? (1)

Ethernet is the traditional protocol used to connect devices in a wired LAN. It defines how data should be physicallly transmitted between different devices, using MAC addesses to determine which device the data should be sent to.

What do Wi-fi protocols determine? (3)

- The frequency band and channel that should be used - Data transmission rates - How devices should be authenticated when they attempt to join a network