1.3 - Networks Flashcards
What is a Local Area Network (LAN)?
A network in a small geographical area (same building or a small site)
Who owns the infrastructure for a LAN?
Network owner
The organisation using it
What is a Wide Area Network (WAN)?
A network in a large geographical area (across a country or multiple e.g. The Internet)
Who owns the infrastructure for a WAN?
Third parties
What affects network performance?
- Bandwidth
-Interference (e.g. thick walls)
-Transmission media
-Amount of data being transmitted
-Error rate
-Latency
What is bandwidth?
The maximum amount of data that can be sent across a network at once. Measured in bits per seconds
What is latency?
The delay from transmitting media to receiving it. Caused by bottlenecks (a junction where data gets held up) in the infrastructure of the network.
What are the advantages of using a Client-Server network?
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Controlled centrally: easy to backup data and update software
-Makes access to files more secure as sensitive data is stored on the server rather than on individual clients - Hardware, software and resources can be shared across the network
- Easy to add new clients to the network
What are the disadvantages of using a Client-Server network?
- Traffic congestion will cause network to slow down
- Reliant on server: If the server fails, the whole network fails and users will lose access
- IT technicians required to maintain the network
- Malware can spread from the server to all computers on the network
What are the advantages of using a Peer-to-Peer network?
-
Simple setup: no server is required
-Cheaper: No specialist staff or expensive hardware required - Not dependent on a server
- Easy to share files between systems
What are the disadvantages of using a Peer-to-Peer network?
-
No central device to manage security or backups
-Less secure as security software is individually managed - More devices = decrease in performance
What are data packets?
Files broken down into smaller parts to be transferred across a network
What is in the header of a data packet?
- Source address
- Destination address
- Packet number
- Protocol
What is in the payload of a data packet?
The data itself
What is in the trailer of a data packet?
A checksum: a calculation to see if any errors or corruption has occurred during transmission
What is a network topology?
Layout of computer systems on a local network
What is a star topology?
Each computer system is connected to a central device (hub or switch)
What are the advantages of a star topology?
- Improved security as data packets are sent directly to and from the hub / switch
- Easy to add new systems
- Fast transfer speeds as there are minimal network collisions
What are the disadvantages of a star topology?
- Extra hardware required
- If the central system fails, the whole network will fail
What is a mesh topology?
Each computer system is connected to every other computer system
What are the advantages of a mesh topology?
- Not reliant on central node: If one cable or system fails, data packets can take an alternative route
- Can withstand large amounts of data traffic
- New systems can be added without disrupting the entire topology
What are disadvantages of a mesh topology?
- Large amount of cables mean it can be expensive to install and maintain
- Redundant cabling
What kinds of network hardware are there?
- Wireless Access Point (WAP)
- Router
- Network Interface Card (NIC)
- Transmission medium
- Switch
What is a Wireless Access Point (WAP)?
Links wireless and wired networks
What does a router do?
Transfers data packets between networks
What does a switch do?
Connects devices together on a LAN
-Sends data between computers on a LAN
-They segment the network by forwarding traffic to the correct location
-Switches learn which devices are connected and understand how to forward traffic in an intelligent way
What does a Network Interface Card (NIC) do? What does it contain?
They use a protocol to determine how the connection should work. They allow a device to connect to either a wired or wireless network.
They contain a unique hardware address, called a MAC address
What kinds of transmission media are there?
- Ethernet cables
- Fibre Optic cables
- Coaxial cables
What are ethernet cables?
Are copper cables used on a LAN to transfer data
Ethernet is a wired networking standard to carry electrical signals between devices
What are Fibre Optic cables?
Very fast but expensive and fragile cables with higher bandwidth than copper cables, used to send data quickly along a WAN as pulses of light
What are coaxial cables?
Older, slower copper cables
What is the Internet?
A global network of interconnected networks
What are IP addresses used for?
Locate devices on the Internet geographically
What is an IPv4 address?
- 4 values where the largest number for each value is 255, each separated by a dot
- E.G: 128.10.2.255
What is an IPv6 address?
- 8 hexadecimal numbers where the largest value for each is FFFF, each separated by a colon
- E.G: 1A28:724C:1111:4812:FE38:579B:BA34:111B
Give 2 differences between IP addresses and MAC addresses.
- IP addresses are configured in software, MAC addresses are configured in hardware
- IP addresses can be changed, MAC addresses can’t be changed
- IPv4 addresses are 4 bytes long, MAC addresses are 6 bytes long
- IPv4 is written in denary, MAC addresses are written in hexadecimal
- IP addresses are used for routing across the internet/a WAN, MAC addresses are only used within the LAN
What does a Domain Name Server do (DNS)?
When a URL is entered, a DNS looks up its IP address
What do cloud servers do?
Host resources or files that can be accessed through the Internet
What are protocols?
A set of rules enabling devices to communicate
What are networking standards?
Consistent rules that allow computer systems to communicate across networks and/or be fit for their intended purpose
What does Transmission Control Protocol (TCP) do?
Splits data into packets and handles errors
What does Internet Protocol (IP) do?
Routes and assigns IP addresses to data packets
What is Hypertext Transfer Protocol (HTTP/S) for?
Is used to transfer web pages over the internet so that users can view them in a web browser, HTTPS is encrypted
What is File Transfer Protocol (FTP) for?
For sending files
For downloading or uploading a file from or to a server
What is Post Office Protocol (POP) for?
Inbound emails, no server sync
Used to retrieve email, however the email is downloaded onto the device
What is Internet Message Access Protocol (IMAP) for?
Inbound email, mail client syncs with mail server
-Used to retrieve email and it allows the user to view/access the email on the server
What is Simple Mail Transfer Protocol (SMTP) for?
Outbound email (to send email)
What is WiFi and Bluetooth for?
Wireless Internet, WiFi = On a LAN, wireless technology which allows devices to interface with the internet
Bluetooth = for one person, short range wireless technology for communication between two devices that are close together
Describe wired connections in comparison to wireless
Wired connections use physical cables, such as Ethernet and copper or fibre optic wires, and require a network interface card (NIC) to connect to a network.
They are faster and more secure than wireless but restrict movement
Describe wireless connections in comparison to wired
Wireless connections, such as WiFi or bluetooth use no cables but require a wireless network interface card (WNIC).
They allow freedom of movement. However, wireless connections generally have a slower speed, are less secure and can be affected by the computer’s distance from the wireless router and interference.
What is a layer?
A grouping of protocols that perform similar functions
What is the 4-Layer TCP-IP model?
- Application: Allows humans and software applications to use the same network
- Transport: Makes sure the data is sent and received in the correct order and reassembled at the destination
- Network: Optimal route for data is calculated
- Data Link: Handles transmission errors and passes data to the physical layer
(Don’t need to know for exam)
Define encryption
Encryption is the process of encoding data so that it cannot be easily understood if stolen or intercepted. (1 mark).
In this process plain text is converted into cipher text by using an encryption key. (1 mark)
The original text can only be understood if the user has the decryption key. (1 mark)
