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