1.3 - Computer Networks, Connections and Protocols Flashcards
What is a Wide Area Network (WAN)?
A network (over a relatively large geographical area) in which the computers communicate using resources supplied by a third party carrier.
What is a Local Area Network (LAN)?
A self-contained network over a relatively small geographical area.
What are the characteristics of a WAN?
Large geographical area; collection of LAN’s; infrastructure between LAN’s leased from telecommunication companies; fibre optics, telephone lines, satellite links used for connection
What are the characteristics of a LAN?
Single site; small geographical area; organisation owns all hardware; fibre-optics, UTP, wireless connection
What affects the performance of a network?
Bandwidth, Latency, Error rate
What is meant by bandwidth?
The amount of data that can be sent and received successfully per second
What is latency?
The length of time a packet of information takes to travel through the network
What is the role of a Network Interface Card (NIC)?
To connect a device to a network.
What is the role of a Wireless Access Point (WAP)?
To allow devices to wirelessly connect to a network.
What is the role of a router?
To route data packets between a LAN and the Internet.
To connect networks, using IP addresses.
To store the IP addresses of the connected networks.
What is the role of a switch?
To connect each node in a network and send data between computers on a LAN.
To use MAC addresses to connect nodes.
To look for the correct MAC addresses as they are being accessed.
What is the Internet?
A collection of inter-connected networks.
What is the Domain Name Service made up of?
Domain Name Servers
What is the role of the DNS in converting a URL into an IP address?
A DNS server translates a web address into an IP address.
When a DNS server receives a request not in its database, the request is passed on to another server until it reaches one with the matching name and IP address.
What is a server?
A powerful computer which provides services or resources required by any clients.
What is a client?
A computer or device that requests services or resources provided by the server.
Types of servers?
File server, print server, email server, web server, database server
What is web hosting?
A service offered by companies in which the facilities need to create and maintain web pages and files for websites are provided.
What is the Cloud?
Services that are remotely delivered over the Internet, for example: to allow the remote storage of files over the Internet.
What are the advantages of the Cloud?
Data and applications can be accessed from anywhere (with an Internet connection); no money needs to be spent on storage for the files as it is done on a remote computer; backing up data is no longer crucial.
What are the disadvantages of the Cloud?
Personal data is stored on another company’s servers; service is unusable if the Internet connection is lost; slow Internet connection results in poor quality of service; people can’t see the level of security and backup.
What is a network topology?
The way in which computers in a network are physically connected.
What are the advantages of a star network?
If a device fails or a cable is disconnected, the rest of the network is unaffected.
It’s simple to add more devices to the network.
High performance and data transmission speed (within the network) as data goes straight to the central device. So all devices can transmit data at once and there are few data collisions.
What are the disadvantages of a star network?
Requires additional hardware (eg: switch), this is expensive.
The network goes down if the central switch fails.
What are the advantages of a mesh network?
No single point of failure; expansion and modification can be done without disrupting the network; data can be transmitted from different devices simultaneously.
What are the disadvantages of a mesh network?
Can involve redundant connections; cabling can be expensive; difficult to maintain and administer
What are the advantages of a wireless network?
Convenient, easy to set up large numbers, cheap
What are the disadvantages of a wireless network?
Slower than wired networks; relies on signal strength to WAP; less secure than wired, signal can be obstructed
What is encryption?
The encoding of data so that plaintext is scrambled into cipher text, which can not be understood without a key to decrypt.
What is the format of IPv4 addresses?
32- bits; 4 numbers (0-255) separated by ‘.’
What is the format of IPv6 addresses?
128- bits; 8 sets of 4 hex values; sperate by ‘:’
What are the roles of standards?
To provide rules for areas of computing; to allow hardware/software to interact across different manufacturers/products
What is a protocol?
A set of rules for transferring data, and governing network operations
What is Hypertext Transfer Protocol (HTTP) used for?
Accessing and receiving web pages via the Internet
What is Hypertext Transfer Protocl Secure (HTTPS) used for?
Accessing and receiving web pages via the Internet, with encryption.
What is the File Transfer Protocol (FTP) used for?
Sending or retrieving files from a server.
What is the Simple Mail Transfer Protocol (SMTP) used for?
Sending emails to an email server.
What is the Post Office Protocol (POP) used for?
Retrieving emails from the email server and downloading them onto the computer, then removing the email from the server.
What is the Internet Message Access Protocol (IMAP) used for?
Retrieving an email from the email server, without removing it from the server.
What is the role of the Internet Protocol (IP)?
To route data packets across a WAN.
What is the role of the Transmission Control Protocol (TCP)?
Provides error-free transmission between 2 routers.
What is a layer?
A division of network functionality
What are the advantages of using layers?
Layers are self-contained, so the functionality of one layer can be changed without affecting the functionality of another layer; complex problem is broken down into a simple problem; devices can be manufactured to work at a simple layer.
What are the advantages of a client-server network model?
Easier to keep track of files as they are stored centrally
Easier to perform back-ups
Easier to install and update software
Easy to manage network security
What are the disadvantages of a client-server network model?
Expensive to set up (servers are expensive) and needs IT specialists to maintain the network
Dependence on the server
The server may become overloaded if too many clients are accessing it at once
What are the advantages of a peer-peer network?
Easy to maintain - no server needed
No dependence on server
What are the disadvantages of a peer-peer network?
No centralised management for updates, security and backups.
Copying files between devices creates duplicate files - it’s easy to lose track of what’s stored where and which files are up-to-date.
Peer machines are less reliable and data may be lost if one fails.
Machines are prone to slow down when other devices access them.
