GCSE OCR Computer Science Networks
Terms in this set (39)
What is a network?
It is a collection of computer systems linked together.
What is a node?
It refers to each device on a network
What are the benefits of network?
- work to be shared out between nodes
- easy communication between users
- sharing of files
- sharing of peripheral devices like printers
- monitoring of user activity
- access control and other security related features
- centralised administration and updates
What is a LAN?
LAN is local area network
What is a WAN?
WAN is wide area network
What is the difference between LAN and WAN?
LAN covers a small geographical area located on a single site whereas WAN is used to connect LANs in different geographical locations
Hardware for LAN is owned by the organisation while organisations hire infrastructure from telecommunications companies who manage it
LANs are usually wired or wireless while WANs are usually connected using fibre or copper telephone lines, satellite links or radio links
What is the biggest WAN in the world?
What factors affect the performance of networks?
1. Available bandwidth
2. Number of users
3. Traffic volume e.g. streaming video
4. Wired or wireless connections. Wired connections are more reliable and faster than wireless connections
5. Choice of hardware
6. Network topology
What affects the performance of wireless networks?
1. Signal quality
2. Range of device
3. Amount of interference from other devices
4. Physical obstructions
What is UTP?
Unshielded Twisted Pair. Cable made from copper wiring that are twisted around each other to minimise induction and cross-talk between cables
What are some advantages and disadvantages of wireless networks?
+1. Avoids the need to install cables
+2. Easy connection of devices
-1. Less transmission speed as compared to wired networks as all users share the same bandwidth
-2. Security is a potential problem as wireless signals can be easily intercepted.
What are 3 different types of wired cables used for networking?
1. Ethernet cables or Unshielded Twisted Pair (UTP) cables
2. Coaxial cable. Single copper wire shielded with with metallic mesh and insulation
3. Fibre optic cables. They transmit data as light.
Name 2 different forms of network
What are the characteristics of a client-server network
1. It is managed by a server which many clients are connected to.
2. Files and software are stored centrally
3. Client-server relationship
What are some pros and cons of client-server networks?
+1. Easier to keep track of files
+2. Easier to perform backups
+3. Easy to install and update software
+4. Easier to maintain software security
+5. Easier to manage network security
-1. Expensive of setup. Needs IT support specialists to maintain network and server
-2. Server dependence. If server goes down, all clients lose access to their work
-3. Potential to overload server with too many clients
What are the characteristics of a peer-to-peer network?
1. All devices are equal
2. Store files on individual devices and share them with others
What are some advantages of peer-to-peer network?
+1. Easy to maintain
+2. No dependence on server
-3. No centralised management. Devices need to install their updates and security individually. Backups are complicated.
-4. Duplicates can be created. It is easy to lose track of the most updated copy of the file and where it is stored.
Name 4 network topologies.
What are some advantages and disadvantages of star topology?
+1. If a device fails or a cable is disconnected, the rest of the network is unaffected.
+2. Simple to add more devices to the network
+3. Better performance as the devices can transmit at once and there are fewer data collisions
-1. Expensive as every device needs a cable to connect to the central switch or server
-2. If there is a problem with the switch or server, the whole network is affected
What is a protocol?
A protocol is a set of rules for how devices communicate and how data is transmitted across the network.
What is a MAC address?
It is a unique identifier for every device on the network
What is an NIC and what is it used for?
NIC stands for network interface controller and it sends and receives signals on the network using a protocol
What is a wireless access point?
This is the point which a wireless enabled device connects to a network
What is a router?
A router is responsible for transmitting data between networks
What is a switch?
Switches connect devices on a LAN
What is a wireless access point (WAP)?
It is a switch that allows devices to connect wirelessly
What is a mesh topology?
A network layout where users are directly connected to each other
What are some advantages of mesh topology?
+1. No single point of failure
-1. Expensive unless you are connected wirelessly
Describe the packet switching sequence
The sending devices splits up the data into packets.
Each packet is given a header to show the order of data
The packet reaches its destination using the TCP/IP protocol via routers.
The receiving device uses a checksum to ensure the data is sent correctly
What are IP addresses?
IP addresses are assigned manually (static) or automatically (dynamic) to devices when sending data over a TCP/IP network
What are packets of data?
This is when data is split into equal sized chunk to be sent between networks
What are some features of these packets?
It consists of a header, payload and checksum number.
The header contains the source, destination address and packet number. The payload is part of the data being sent. The checksum number validates the data and make sure it is not corrupted along the way. Both the sending and receiving data calculate a checksum value using the checksum number. If the values match then the data is received correctly.
What is TCP/IP?
It is the protocol that determines how data is sent over the Internet. It is made up of two protocols TCP and IP.
Transmission Control Protocol sets the rules on how devices communicate on the network. It splits the data into packets and reassembles them once it reaches the receiving device. Responsible for checking that data is correctly sent.
Internet Protocol is responsible for packet switching.
Name some other protocols
1. HTTP - Hypertext transfer protocol - used by web browsers to access websites and communicate with webservers
2. HTTPS - secure version of HTTP
3. FTP - File Transfer Protocol -
4. SMTP - Simple Mail Transfer Protocol - send emails
5. POP3 - Post office protocol
6. IMAP - Internet Message Access Protocol
7. SMTP - Simple Mail Transfer Protocol
Name the 4 network layers and their functions
1. Application data - turns data into websites and applications
2. Transport layer - controls data flow
3. Network layer - Used by routers. Makes connections between networks and directs packets and handle traffic
4. Data link layer - Passing data over physical network in terms of hardware and electrical signals
What are some advantages of using layers?
+1. Helps to break communication network to manageable pieces
+2. Self-contained. Changes to one layer will not affect other layers.
+3. Having fix layers enables manufacturer to make compatible and universal hardware and software
What are the pros and cons of the cloud?
+1. Users can access files from any connected device
+2 Easy to increase storage
+3. No need to buy expensive hardware
+4. No need to employ IT staff to manage hardware
+5. Provides security and backups
+6. Updated automatically
-1. Need connection to the Internet to access files
-2. Dependent on host to backup data
- 3. Data vulnerable to hackers
-4. Subscription fees may be expensive
What is a virtual network?
It is a software based network. It is formed when the physical network's bandwidth is partitioned
What is a virtual private network?
It is a type of virtual network that is used to send data securely over a large network
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