1.3 Computer Networks + Protocols Flashcards
Describe the 2 types of network
1) LAN (local area network): covers a small geographical area. Hardware for infrastructure is owned by organisation.
2) WAN (wide area network): covers a large geographical area. Hardware for infrastructure is owned by a third party
Why use a LAN
. Share files easily
. Share hardware
. Share an Internet connection
. Install software on all computers at once rather than individually
. Use accounts mean people can log on from different physical devices to access the same files
What is the Internet?
A worldwide collection of interconnected networks
What is the world wide Web
A collection of websites that are held on Web servers
What is a client server relationship?
. Managed by a server
. All devices connected are clients
. Files and software are stored centrally on the server
. Clients send requests to the server
. The server responds to requests from the client
. Backups and software updates can be performed centrally
What is a peer to peer relationship
. All devices are equal
. Devices connect directly to each other
. Files are stored on the individual devices
What is mesh topology
. All devices are connected either directly or indirectly to eachother
. Data can be sent along through fastest route from one device to another
. The network cannot fail if one connection is lost ad an alternative route will be available
. Expensive to used wired connections but practical for wireless
What is star topology
. All devices are connected to a central switch or server that controls the network
LAN hardware
1) NIC (network interface controller): allows a device to connect to a network
2) router: responsible for transmitting data between networks
3) switch: holds the MAC address of each individual device on the network
4) cables: standard network cables withing LANs are twisted-pair copper cables. Copper cables are low cost but can be affected by interface. Fibre option cables offer great bandwidth and are not affected by interface
5) WAP (wireless access point): wireless transmitter that receives data via a physical connection to the network, then converts this into radio waves
Factors that can affect performance of networks
1) Bandwidth: this is the amount of data thar can be transferred at a given time. Greater bandwidth, better network
2) wired/wireless: wired connections are more reliable. But wireless gives freedom of movement
What are the risks of WiFi?
1) criminal activity: an unauthorised user can use the wireless connection to hack into the network and cause damage by planting viruses or launching denial of service attacks
2) bandwidth stealing: by using the networks Internet connection to download music, games and other software, streaming of music or video, outside intruders can slow a network down and reduce employee productivity
3) Confidentiality: if any network information is not encrypted before transmission, an intruder can gain access to confidential information
How can you make WiFi more secure?
1) hide the SSID: the SSID is the service set identifier of a wireless network. This displays the name of your WiFi network when people search for WiFi connections. Hiding the SSID means that it won’t be shown
2) restrict access: the unique decide MAC address can be used to create a list of recognised devices that are allowed to connect
3) use WPA: wpa is a wifi protected access encryption. This prevents data and signals being read by an outsider. Devices need to be authenticated before they are connected and provided with keys to decrypt data
What is the MAC address
A unique identifier given to all pieces of hardware at manufacture. They are 48 or 64 but binary numbers that are usually displayed in their hexadecimal form.
What is the IP address
A unique number that is assigned to a device when it joined a network. Used to enable communications between networks
Explain DNS
DNS is a domain name server
1) user enters a domain name into browser software. Browser contacts the dns server to request IP address that matches the domain name
2) if the dns server has the IP address, it will give this to the browsers. If not, the dns server will ask another dns server
3) the dns server has the IP address for the domain name in memory. This is passed back to the pervious dns server.
4) dns server will store the IP and domain name data in case it is asked for again
5) the browser can now use the IP address to access the Web server where the desired website was held
