Mock Flashcards
Describe the main features of a client server network
∆ Controlling computer / network server
∆ Handles the processing requests from the other computers on the network
∆ For resources
∆ And controls security across the network
Describe the main features of a star network
∆ Multiple nodes are directly connected, each via its own cable to the hub/server which is in charge of communication
∆A node sends data to the hub
∆ The hub determines the recipient
∆The hub forwards data to the recipient
Describe the main features of a ring network
∆ The nodes are connected in a loop
∆ Each node is connected to two other adjacent nodes
∆ A special message called a token (data) is passed from node to node
∆ Until it reaches its intended recipient
∆ Data can only travel in one direction
Describe the main features of a bus network
∆ All nodes are connected onto a main cable
∆ Data can be transmitted bi-directional
∆Terminators are used at both ends of the main cable
∆ Each node can transfer data directly to any other node by sending it on the main cable
📝 Evaluate the star topology and the bus topology with respect to data security
⭐️ Network:
∆ Has a central dedicated fileserver, each node is connected directly to the hub by its own cable. The fileserver controls all network communication and the transfer of data packets
∆ The star network is more secure. Data packets are sent from fileserver to node directly via dedicated connection. Fileserver controls all security only intended recipient receives the data packet
🚎 Network:
∆ Has a main backbone to which all nodes are connected, and a terminator at both ends. A node sends a data packet to another node via the backbone
∆ Bus network is less secure. No central control of security, all nodes could access data packets on backbone, data packets travel in both directions
📝 Compare the impact of cable failure on data transmission over a star network and a bus network
∆⭐️ Each device is connected to a central hub by it’s own cable
∆🚎 All devices are connected to a backbone cable
Comparison:
∆ ⭐️ If a cable fails only a single device is affected
∆ 🚎 If the backbone fails all communication is affected, if a connecting cable fails only that device is affected
Why are communication standards required?
∆ To enable different hardware devices to pass data to one another
∆ securely and coherently
∆ using agreed formats
Describe the main features of the Open Systems Interconnection (OSI) model
The OSI model:
∆ Consists of an abstract model of networking and a set of specific protocols
∆ It defines a layered protocol (7 layers)
∆ Each layer deals with specific functionality
∆ Control is passed from one layer to the next
∆ Each layer interacts directly only with the layer immediately beneath it and provides facilities for use ny the layer above
Describe the Data Link layer of the OSI model
∆ Deals with functions such as error detection, correction and creating data blocks
∆ Converts each outgoing packet into a series of bits
∆ Interacts with the network/physical layers
Describe the application layer of the OSI model
∆ Presents information to the end user
∆ Deals with functions such as data transfer, messaging, operating system functions, end user interface
∆ Interacts with the presentation layer
Briefly describe the TCP/IP protocol.
Transfer Control Protocol / Internet Protocol supports connectivity between LANs and WANs. It allows all Internet users and providers to communicate irrespective of the hardware. Providers have unique addresses.
Describe the purpose of the IP Layer
∆ Delivers the data packets to the appropriate node using the IP address
∆ Treats each data packet independently
Describe the purpose of the TCP layer
∆ Enables two hosts to to establish a connection and exchange data. It is responsible for reliability and correct delivery
∆ It converts a message into data packets containing destination address
∆ That is transmitted over a network to the destination computer
∆Then is reassembled so that the message can be read by the recipient
Describe the main features of RFID technology
∆ Data relating to a product is stored on an RFID tag attached to the product
∆ RFID tag contains data programmed into small computer chip
∆ Tag activated by radio waves emitted from RFID reader
∆ Tag sends data stored in its memory back to the reader
∆ Active or passive technologies
Describe checksum as a method of error detection method
Calculated by adding together all the bytes to make a block of data eg. of 256 bytes
Checksum is recalculated after data transmission
If the recalculated checksum is different there has been an error
Some types of checksum may automatically correct error.
Evaluate the use of parity bits in error detection
An additional bit is calculated from the other bits in a byte, set to make total number of bits odd or even. The parity bit is checked after data transmission and compared to original, if they are different an error has occured and retransmission is requested
What is CRC
A special type of checksum applied to a block of data
An algorithm is applied to block and checksum applied to block
Recipient applies same algorithm and checksum and compares to already appended result
If they do not agree data has not been received correctly.
Retransmission requested
What is echo checking?
When data is received and a copy sent back to transmitter
Where it is compared with original
If it differs from original it is transmitted
Echo checking is an automatic process
