3.5 Flashcards
(33 cards)
Define Computer Network.
A computer network is a collection of computers linked together to facilitate communication and the sharing of resources.
What are some advantages networks?(5)
+ Share resources like printers and scanners
+ Software can be distributed across the network rather than having to install it on each individual computer
+ All files can be backed up centrally
+ Folders and files can be stored on a file server so they can be accessed by authorised users from any computer on the network.
+ Internet connection can be shared and any authorised user on the network can use email.
What are some disadvantages of networks?(5)
- If the file server goes down, no one can access their files or do any work.
- Network faults could lead to loss of data
- The larger the network becomes, the more difficult it is to manage; specialist staff may be required
- Viruses may be able to infiltrate the network and infect every computer
- As network traffic increases, performance degrades so accessing resources may become slow.
What are the properties of a wired network?(3)
File transfer speeds are generally faster with a wired connection.
Wired connection are not obstructed by walls and ceilings if cables are laid.
Wired tethers user to a single point.
More secure than wireless because they are harder to hack into.
What are the properties of a wireless network?(2)
Users can move around freely.
Generally cheaper than wired because no ethernet cables.
Easy to add new devices.
Can be obstructed through walls.
Describe a WAN?(3)
A Wide Area Network is a collection of computers and network connected together using resources supplied by a ‘third party carrier’ such as BT.
It uses cables, telephone lines, satellites and radio waves to connect the components which are usually spread over a wide geographical area.
WANs tend to be under collective or distributed ownership and are not necessarily owned by one organisation.
Describe a LAN?(3)
A Local Area Network usually covers a relatively small geographical area. It consists of a collection of computers and peripheral devices connected together, often on a single site.
For example, schools may use a LAN connecting the computers in the buildings across the site.
A LAN is usually owned and managed by a single person or organisation.
Describe a PAN?(2)
A Personal Area Network is a computer network used for data transmissions among devices such as computers, cell phones and laptops.
The most common kind of technology used in a wireless PAN is Bluetooth, which uses short-range radio waves over distances up to roughly 10 metres.
What are routers and switches?(2)
A switch is a component of a LAN that knows the MAC dresses of each individual device connected to it locally. Its function is to send the packets only to the intended recipient, using its MAC address.
A router is designed to route data packets across a WAN such as the internet. Packets are passed from router to router to their destination. If a packet is routed for a computer in a LAN it will be routed to a switch.
Purpose of a NIC?(2)
Network Interface Card. Required to connect any network-enabled device. It contains MAC address. Has either a wired connection using an Ethernet cable or a wireless connection.
All devices that can connect to a network have a NIC.
Purpose of a MAC address?(2)
Media Access Control address. Each Network Interface Card has a MAC address assigned to it. by the manufacturer. A computer may have more than one MAC address, one for wire Ethernet and one for wireless.
A MAC address is a 48-bit address written as 12 Hex numbers - the first 6 identify manufacturer, and the next 6 are unique to the device.
Purpose of an IP address?
When connected to a network each device is given a unique IP address. Routes the individual packets from source to destination via routers.
What is a wireless access point?
Uses a radio transceiver to allow wireless connections to a network.
What is a packet?
A small unit of data, contains a header contains:
IP address it is going to, and the IP address it has come from
Sequence number
Total number of packets in transmission
Error checking data
What is packet switching?
Packets are usually sent to their destination along different routes, and then reassembled in the right order when they arrive. This is packet switching.
What are the differences between Star Networks and Bus Networks?(3)
Bus Networks are much cheaper than Star Networks.
Bus Networks also don’t rely on a central node.
Star Networks have more consistent performance and security - data is received only by the node for which it is intended.
Star Networks are also much quicker than bus networks as more devices are added.
Star Networks are easier to manage because cable failures are hard to isolate on Bus Networks.
Star Networks continue to function if one cable fails, but in Bus Networks if one cable fails, the whole network is affected.
What is TCP?(2)
Transmission Control Protocol is the standard internet protocol for sending files and documents.
It guarantees that all information will be sent to the recipient in a trade off for speed.
What is UDP?(2)
User Datagram Protocol is similar to TCP, but because messages are sent in chunks instead of packets it is often faster, allowing for gaming or video calls over the internet.
UDP transmission also maintains an open connection between the sender and the recipient for the duration of communication, this two-way communication is what makes it faster.
What is FTP?(2)
File Transfer Protocol governs the transmission of files across a network and the internet.
FTP uses separate control and data connections between the client and server
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What is SMTP?(2)
Simple Mail Transfer Protocol governs the sending of email messages between servers.
After they are sent to one server to another the messages can then be retrieved using IMAP.
What is HTTP and HTTPS?(2)
Hypertext transfer Protocol (secure) is used for accessing and receiving web pages in the form of HTML.
HTTPS includes secure encryption of the information so that it cannot be understood if it is hacked by a hacker. Banks use HTTPS.
What is IMAP?(2)
Internet Message Access Protocol governs retrieving emails from email servers.
Emails are stored on a server but IMAP allows users to view and manipulate the messages as if they were stored locally on their own computers.
What is IP?(2)
The IP protocol identifies the location of a device on the Internet and routes the individual packets from source to destination via routers.
What are the four layers of Network?(4)
Application layer - HTTP(S), FTP, SMTP, IMAP operate here.
Transport layer - TCP, UDP operate here.
Internet layer - IP operates here
Link layer
Internet.
