Ict test 1 chapter 2 Flashcards
What is a packet?
a small unit of data
Why does data need to be broken down into packets to be transmitted
The amount of data that is stores in a file can be very large , If you tries to transmit this data from one device to another, all at once, this just would be possible nor practical. The wires or radio used would simply not be able to accommodate sending such large amount of data at a single time. Therefore , for the data in a file needs to be broken down into packets
What are the three different sections in a packet?
Packet header
Payload
Trailer
What is a IP address?
The unique address given to a device when it is connected to a network
Why is the IP address important?
Without this address , the hardware transmitting the data would not know where to send the data
What is the payload?
The payload is the actual data being sent from the file
What is the Trailer?
The Trailer is a section of a packet of data that contains information about any error checking methods that may be used
What is the Packet Header?
The Packet header is a section of a packet of data that contains information about the contents of the packet and its destination
State everything the Packet header contains?
Destination address
Originators address
Packet number
What is packet switching?
a method of transmitting data packets across a network. Each data packet is able to take an individual pathway across a network
What is a Router?
A router is the device that controls which pathway will be used to transmit each packet
What is a Network?
Computers and devices that are joined together using cables or wireless technology
Which method of data transmission sends data along a single wire?
Serial
Which method of data transmission sends data multiple bits at a time?
Parallel
Name two advantages and two disadvantages involving transmitting data using serial data transmission?
Advantages
As data is sent one bit at a time, it should arrive in order of sequence. This means there is less chance of the data being screwed
Only one wire is needed for serial transmission cable, therefore, it is cheaper to manufacture and also cheaper to buy
Disadvantages
As data is sent one bit at a time, the transmission of data will be slower
Additional data may need to be sent to indicate to the receiving device when data transmission has started and stopped. This is Called a start bit and stop bit
Name two advantages and two disadvantages involving transmitting data using Parallel data transmission?
Advantages
As data is sent multiple bit at a time, the transmission of data will be quicker
Many computers and devices use parallel data transmission to transmit data internally. Therefore ,there is no requirement to convert this to serial data transmission to transmit the data across a network
Disadvantages
As data is sent multiple bits at a time, bits do not arrive in order and need to be recorded after transmission. This increases the chance of the data being screwed
Multiple wires are needed for Parallel transmission cable, therefore, it is more expensive to manufacture and also more expensive to buy
What does USB stand for?
Universal Serial Bus
What is a USB port?
a socket that is a part of a device that enables you to insert a USB cable
What is a USB cable?
A type of transmission media that uses a USB method to transmit data
What is a USB connection?
A collective name for using a USB cable plugged into a USB port to transfer data from one device to another
What is a USB device?
the name of a device that plugs into a USB port on a computer
Name two advantages and two disadvantages of using the USB interface
Advantages
The speed of the USB is relatively high ,so data can be transferred quickly
It is a simple interface. The USB cable to device can only fit into the USB one way. Therefore, it means less errors in connecting devices are likely to be made
Disadvantages
The length of the USB cable is limited, normally to 5 meters
The transmission speed is relatively high for a USB connection, But it isn’t as High as other types of connection, such as ethernet
What is Parity check?
A type of error detection method that adds an additional bite each byte to create a odd or even sum.
What is Checksum?
A type of error detection method that performs a calculation on data to create a checksum value. Checksum values are compared after transition to see if they match
What is Echo check?
a type of error detection method that sends a copy of the transmitted data back to the sender to be compared with the original data sent
What does ARQ stand for?
Automatic repeat request
What is ARQ?
A type of error detection method that uses acknowledgement and timeout to see if data has arrived correctly after transmission
What is acknowledgement?
a message that is sent from one device to another to indicate whether data is received correctly
What is timeout?
a period of time that i set and used to wait for an acknowledgement to be received
What is Check Digit?
a type of error detection method that is used for a data entry. A calculation is performed on the data entered to create a value. Check digit values are compared to see if the data entered is correct
What is encryption?
a method of securing data for storage or transmission that scrambles it and makes it meaningless
What is the name given to data BEFORE encryption?
Plain text
What is the name given to data AFTER encryption?
Cipher tex
What is the encryption key?
a type of algorithm that is used to encrypt data
What are the two main methods of encryption?
Symmetric and Asymmetric
State the process for Symmetric encryption.
The process for symmetric encryption is:
Plain text is encrypted into cypher text using a encryption key
The cipher text and the encryption key are then sent separately to the receiving device
The same key is then used to decrypt the cipher text back into plain text form
State the process for Asymmetric encryption.
The process for symmetric encryption is:
Plain text is encrypted into cypher text using a public key.
The cipher text is transmitted into the receiving device
the cipher text cannot be decrypted using the public key, it is decrypted using a private key
