Computer Systems (III) - Networks Flashcards
What is a network?
Two or more electronic devices that are connected together for the purpose of communication
How are networks connected?
By a wired medium such as Ethernet cables or wireless medium, such as WiFi
What is a computer or device that is not connected to a network known as?
Stand-alone
List the advantages of networking devices
File sharing
Hardware sharing
Communication
Roaming access
List the advantages of networking devices on larger networks (businesses / schools)
Centralised maintenance and updates
Centralised security
User monitoring
Levels of access (different user rights)
List the disadvantages of networking devices
Cost
Management
Spread of malware
Hacking
What does LAN stand for?
Local area network
What does the following show?
A LAN
What are the properties of a LAN?
A LAN is a network that is geographically confined to one building or site
What does WAN stand for?
Wide area network
What does the following show?
A WAN
What are the properties of a WAN?
A WAN covers a large geographical area
Most WANs are made from several LANs connected together
The Internet is a global WAN
What is bandwidth when referring to network performance?
The amount of data that can be transferred at any given time, e.g. 500 Mbps
How can bandwidth, and therefore network performance, be increased?
Too many devices sharing the bandwidth of the network will cause congestion and slow performance
Bandwidth can be limited to devices
Wired (fibre versus copper) / WiFi signal can impact as can the hardware / topology
What hardware components are needed to connect a computer / device to a network?
Network interface controller (NIC)
Transmission medium (wired / wireless)
Connection point (router / hub / switch / WAP
What is a NIC?
Network interface controller (internal hardware allowing a device to connect to a network)
Can be separate cards but often built into the motherboard (wired / wireless)
What is a switch?
Switches connect devices onto a LAN
They receive data (units called frames) from one device and transmit this data to other devices
What is a router?
Routers transmit data between networks
Data (packets) are directed to their destination
They are used to connect LANs to the Internet
Name a common wired transmission medium for data transfer between computers
Ethernet (CAT 5e / CAT 6) – twister pair cables
Name a common transmission medium to carry a TV signal
Coaxial cable
How do fibre optics work and what advantages do they have?
Data transmitted as light – they suffer from no interference so can transmit over very large distances
*Are expensive
How does wireless work?
Radio waves transmit data
Wireless Access Point (WAP) devices allow connections (a switch)
Wireless subject to interference and limited range
What are the properties of WiFi?
Multiple devices to the same LAN
Range up to 100m
High bandwidth (for wireless)
Often used in the home (routers / desktops / laptops / smart TVs)
What are the properties of Bluetooth?
Direct connection between two devices
Range around 10m
Low bandwidth
Often found in headphones / wearables
What is a client-server network?
A network managed by a server, to which clients connect
Files and software stored centrally
Profiles / passwords to access
What are the advantages of a client-server network?
Easier to keep track of files
Easier to backup
Easier to install updates / network security
Reliable and always on
What are the disadvantages of a client-server network?
Expensive to setup
IT specialists needed to maintain
Server dependence – clients lose access if goes down
Server can become overloaded and slow
What is a Peer-to-Peer (P2P) network?
Devices all being equal, connecting directly
Files stored on individual devices, and shared
Often used in the home between devices / connect to a printer
What are the advantages of a Peer-to-Peer network?
Easy to maintain
No dependence – if one device fails, the whole network isn’t lost
What are the disadvantages of a Peer-to-Peer network?
No centralised management (security / backups more complicated)
Duplicates of files when copied between devices
Less reliable peer machines – one breaking may cause data loss
Machines slow when other devices access them
A device connected to a network is known as what?
A node
What is a network’s topology?
The arrangement of the network
What are the two most common network topologies?
Star topology
Mesh topology
What does the following show?
A star topology
What are the properties of a star topology network?
All nodes indirectly connect to each other (through switches)
The switch acts as a central point, through which all communications pass
What are the advantages of a star topology network?
Each node is separately connected – failure of one node doesn’t impact others
New nodes easily added
High performance – message passed only to intended recipient
What are the disadvantages of a star topology network?
Whole network fails if the switch fails
Lots of cabling is required - expensive
What are the two types of mesh topology?
Full mesh topology
Partial mesh topology