Networks & Topologies Flashcards
All 39 cards in this deck
What is a LAN?
A network covering a small geographical area, e.g. a single building or site, where all the hardware is owned and managed by the organisation.
What is a WAN?
A network covering a large geographical area that connects LANs together, using external infrastructure hired from telecommunications companies.
What do the abbreviations LAN and WAN stand for?
Local Area Network and Wide Area Network.
Give one common example of a LAN and one common example of a WAN.
LAN: a school or home network. WAN: the Internet, or a bank's network linking its branches.
Give two reasons why a network contained within one youth centre building is a LAN and not a WAN.
It covers a small geographical area (a single building), and all the hardware is owned/managed by the youth centre with no external infrastructure used.
True or false? The infrastructure of a WAN is normally owned by the organisation that uses it.
False. A WAN uses external infrastructure hired from telecommunications companies; only a LAN's hardware is owned by the organisation.
What is bandwidth?
The amount of data that can be transmitted over a connection in a given time, measured in bits per second.
State three factors that can affect the performance of a network.
Bandwidth available, number of devices connected, the transmission media used, and interference.
What effect does connecting more devices have on a network's performance?
Performance drops, because the available bandwidth is shared between more devices and more data collisions occur.
How does the transmission media used affect network performance?
Higher quality media carry more data with fewer errors, e.g. fibre optic cable gives higher bandwidth and less interference than copper cable.
State two ways the performance of a slow network could be improved.
Increase the bandwidth of the connection, and reduce the number of devices connected at once (or upgrade the transmission media, e.g. to fibre optic).
True or false? Interference can reduce the performance of a wireless network.
True. Thick walls, distance and other devices using the same channel weaken the signal, so data has to be resent.
What is the role of the server in a client-server network?
It provides services and resources to clients when they request them, e.g. file storage, web pages, printing, and it manages user accounts and security.
What is the role of a client in a client-server network?
It requests services and resources from the server, and is the computer the user works on.
What are the roles of the computers in a peer-to-peer network?
All computers are equal peers; each one acts as both client and server, sharing files and resources directly with the others.
True or false? In a peer-to-peer network one computer acts as a central server for the others.
False. There is no central server; every computer has equal status and shares resources directly.
Give two advantages of a client-server network over a peer-to-peer network.
Files and backups are managed centrally on the server, and security/user accounts can be controlled centrally by an administrator.
A home with three computers wants to share files cheaply and has no technical staff. Which network model is recommended, and why?
Peer-to-peer; no expensive dedicated server is needed and it is simple to set up and maintain.
What task does a switch perform in a network?
It connects devices together and directs data only to the destination device, using a table of the MAC addresses of connected devices.
What task does a router perform?
It connects different networks together and directs data between them using IP addresses, e.g. connecting a LAN to the Internet.
What task does a wireless access point (WAP) perform?
It allows devices to connect to the network wirelessly, transmitting and receiving radio signals.
What task does a NIC (Network Interface Controller/Card) perform?
It allows a single device to connect to a network, giving it the hardware and MAC address needed to send and receive data.
What is meant by transmission media in a network?
The cables or channels that carry the data between devices, e.g. copper (Ethernet) cable or fibre optic cable.
What hardware is needed to connect several stand-alone computers into a wired LAN?
A NIC in each computer, a switch to connect them, and transmission media (cables) — plus a router if the LAN needs Internet access.
What is the Internet?
A worldwide collection of interconnected computer networks — a network of networks.
What is a DNS (Domain Name Service) and what does it do?
A service made up of many Domain Name Servers that converts a URL (domain name) into the IP address of the web server.
What is meant by hosting?
Storing a website or files on a server (usually owned by a hosting company) so that they can be accessed by others over the Internet.
What service does a web server provide?
It stores web pages and sends them to client devices that request them.
What is meant by 'the Cloud'?
The remote provision of services such as storage, software and processing, accessed over the Internet rather than held locally.
Give one advantage and one disadvantage of a business storing its files in the Cloud.
Advantage: files can be accessed from any device with an Internet connection, and backups are handled by the provider.
Disadvantage: no access to the files if the Internet connection fails.What is a star topology?
A topology in which every device is connected by its own connection to a central device, usually a switch.
What is a mesh topology?
A decentralised topology where every device is connected to one or more other devices (in a full mesh, to every other device), giving multiple routes for data.
What are the steps to draw a star topology?
e.g. 4 computers and 1 switch
- Draw and label the central device: the switch.
- Draw and label the other devices around it: the 4 computers.
- Join each device to the switch with one line and add no other connections: 4 lines in total.
Give two advantages of a star topology.
Few data collisions so good performance, and devices can be added or removed without affecting the rest of the network.
True or false? In a star topology, if one cable fails the whole network stops working.
False. Only the device on that cable loses its connection; it is failure of the central switch that brings down the whole network.
Give two disadvantages of a (full) mesh topology.
It needs a large amount of cabling/connections so is expensive, and it is complex to set up and maintain.
A network must keep working even if one connection or device fails. Which topology should be recommended, and why?
A mesh topology, because there are multiple routes between devices so data can take another path — there is no single point of failure.
True or false? A DNS is a single computer that stores every domain name in the world.
False. A Domain Name Service is made up of multiple Domain Name Servers that share the work of converting URLs to IP addresses.
True or false? A mesh topology needs a central switch to control communication between the devices.
False. A mesh is decentralised — devices connect directly to one or more other devices, giving multiple routes for data.