Networks Flashcards
Computer Network
When two or more computers are connected together through a communication medium, either physically using a cable or wirelessly.
What is the purpose of a Computer Network?
To exchange information and data and to share network resources like printers.
Server
A powerful computer that provides services to the other computers on the net work
Client
Computers that use the service of a server. Less powerful than the server.
Communication Medium
This describer how the computers are connected and provides a communication channel along which data can be sent.
Guided Medium: Cables- fibre optic, coaxial, CAT6
Unguided Medium: Wireless.
Network Adaptor
Can provide a wired and wireless connectivity.
Commonly referred to as a NIC- Network Interface Card
Protocols
A formal set or written rules that control the communication process. There are different protocols for different purposes: mail, file transfer.
TCP
Transmission Control Protocol
Breaks data into small units called packets to be sent across the internet, puts packets in correct order at receiving end.
IP
Internet Protocol
Provides an addressing scheme that is used to identify individual computers/networks on the internet.
Mail protocols
SMTP Simple Mail Transfer Protocol Sends mail POP3 Post office protocol Receiving mail
HTTP
Hypertext Transfer Protocol
Allows you to send website pages
HTTPS
Secure protocol
Used for secure connections such as online banking
FTP
File Transfer Protocol
Used to copy files from one computer to another over a network.
Advantages of a Computer Network
- Sharing devices such as printers saves money.
- Files can easily be shared between users.
- Site (software) licences are likely to be cheaper than buying several standalone licences.
- Data is easy to backup as all the data is stored on the File server.
- Security is good - users cannot see other users’ files unlike on stand-alone machines.
Disadvantages of a Computer Network
- Purchasing the network cabling and file servers can be expensive.
- Managing a large network is complicated, requires training and a network manager usually needs to be employed.
- Virus can spread to other computers throughout a computer network.
- There is a danger of hacking, particularly with wide area networks. Security procedures are needed to prevent such abuse, e.g. a firewall
- The network has to be administrated.
WAN
Wide Area Network
It is created when LANs are connected.
Wide area network. The internet is a WAN.
Uses services of telecommunications companies i.e. BT, Virgin media
LAN
Local Area Network A LAN (local area network) is a network of computers within the same building, such as a school, home or business. Uses physical cable or wireless.
PAN - WiFi - MiFi
Personal area network
Interconnects devices centred around an individual persons workspace- within 10m
Uses wireless technology such as Bluetooth
MIFI - wireless devices that enable multiple users to share a single mobile broadband connection while they are on the go.
i.e. personal hotspot
Network Topology
Defines the way in which all network devices are interconnected to create a LAN.
There are three main types: Bus, Star
Most used topology?
Star topology is most commonly used.
What is a bus topology?
In a bus network all the workstations, servers and printers are joined to one cable (the bus). At each end of the cable a terminator is fitted to stop signals reflecting back down the bus.
What is a star topology?
In a star network each device on the network has its own cable that connects to a switch or hub. A hub sends every packet of data to every device, whereas a switch only sends a packet of data to the destination device.
Advantages of Bus topology
- Easy to install
- Cheap to install, as it doesn’t require much cable
Disadvantages of Bus topology
- If the main cable fails or gets damaged the whole network will fail.
- As more workstations are connected the performance of the network will become slower because of data collisions.
- Every workstation on the network “sees” all of the data on the network - this is a security risk
Advantages of star topology
- Very reliable - if one cable or device fails then all the others will continue to work.
- High performing as no data collisions can occur
Disadvantage of star topology
- Expensive to install as this type of network uses the most cable (network cable is expensive)
- Extra hardware required (hubs or switches) which adds to cost.
- If a hub or switch fails all the devices connected to it will have no network connection
Benefits of a wireless network
Portable, no wires
Drawbacks of a wireless network
Less secure
Slower connection speed poor reception.
Benefits of a wired network
Faster, stronger