3. Networks and Communications Flashcards
What is a standalone computer?
A computer not connected to any networks.
What is a local area network? (LAN)
Usually confined within a local geographic area such as a building or campus. The workstations have network cards or wireless connectivity. They often have shared peripherals (printers). Software and data can also be shared.
Where might you find a LAN?
Schools, colleges, businesses and libraries. Also find small LANs in private homes.
What is a wide area network? (WAN)
Consists of computers that are geographically remote. External communications equipment, such as a telephone line, are used to connect computers. A modem, router or other physical device is needed to connect to the WAN.
What is the largest example of a WAN?
The internet.
What do you need in order to connect to the internet?
An internet service provider (ISP).
Give 4 examples where you would use a WAN.
Universities with multiple campuses a long way from each other. Airline booking systems. National lottery terminals. Automated teller machines (ATM).
Lan/Wan NOTE:
Most LANs are connected to a WAN.
What is a virtual network?
Allows computers to communicate with each other as if they were within a single LAN, but without knowing that they may be part of a bigger network.
What are characteristics of the internet?
It is not the same as the World Wide Web. It’s the infrastructure provided to connect computers together across the globe. It uses the TCP/IP protocol for communication between devices.
Why is the internet an open network?
Because any computer with an external communication link can connect to the internet.
Give 4 uses of the internet.
Email, world wide web, internet relay chat (IRC), file transfer.
What are characteristics of the intranet?
Provides the same services as the internet, but only within one organisation. Secure as it can only be used by authorised people and require username/password. Uses the same TCP/IP protocol as the internet.
Why is an intranet a closed network?
Only computers that are part of the LAN or virtual network will be able to gain access.
Give 4 uses of an intranet.
Internal email, internal web pages, internal chat, file transfer.
What are characteristics of an extranet?
A user can connect to an intranet using a username and password from an internet connected computer. It means people can log onto the intranet from outside, but it adds risk as somebody could hack into it.
What is a client server network?
This requires at least one computer that performs the role of the ‘server’.
Give 4 examples of the roles of a server.
File storage, back up, application sharing, printer management.
Client server network NOTE:
Client computers all connect to a server via a switch or other device. In order to access resources such as files or printers, users are required to log on at the client computers.
What will a user connected to the server on a client server network be able to do?
Have a dedicated amount of storage space that is private to the user. Access to printers. Files, if permission has been granted. Software used within the organisation.
What is a peer to peer network?
Has no central server. Each computer performs its own functions and may share some resources with other computers on the network. All computers are equal. Much easier to set up.
Advantages of client-server?
Back ups and anti virus solutions are managed centrally. Network processing is done centrally, meaning clients have more processing power. Data and applications are available from any client. Software can be deployed quickly.
Disadvantages of client-server?
Servers require a lot of processing power, large hard disks and lots of memory - can be expensive. If the server fails, users lose access. Network manager is required. If applications are run from server, lots of traffic which slows down other tasks.
Advantages of peer to peer?
Network traffic is minimal. Easy to set up. No reliance on single server. Each computer works independently, an ordinary computer will suffice.
Disadvantages of peer to peer?
Software has to be installed on each computer. Some confidential files might be available to all users on a network. The user has to use the same computer each time. All processing is done by each computer, meaning that some tasks may take longer to complete.
What is bandwidth?
It measures how much data can be transferred along a communications channel. The more frequencies available to the communications channel, the more data that can be transferred at once.
How is bandwidth measured?
Official measured as a frequency, but more commonly reported in bits per second (bps)
How many bits in a byte?
Eight
8Mb = ?MB
1
What is a bottleneck?
The smallest bandwidth that exists between the user and the place that data is being downloaded from.
Give an example of a small and large bandwidth example?
Small - sending an eMail. Large - Having a video conference.
Why are coax cables still used in the television industry?
Because of its capacity for high bandwidths.
What does UTP stand for?
Unshielded twisted pair (of cables). [Ethernet].
What are STP’s and what do they do?
Shielded twisted pair (of cables). Where each pair has a metal shield which reduces electromagnetic interference.
What cable do you use for local areas?
Copper cable because it can transmit up to 1Gbps.
Copper cables are cheaper than optical cables but are limited to a range of…
100 metres.
What are optical cables? (Fibre-optic).
Minute glass tubes that reflects light along the length of the tube. Used where more than 100m of cable is required.
What is wireless?
It can consist of many methods such as radio, satellite and infrared. Smaller range of frequencies available. Obstacles such as walls can interrupt wireless signals causing lost packets.
