IGCSE Unit 2

Data Transmission when data is transmitted both ways at the same time

• Serial

• Simplex

• Full duplex

• Half duplex

________ is the term used to describe the message before it is encrypted?

_____________ is unreadable text generated after encryption.

• plaintext

• ciphertext

• encrypted message

• session key

Which of the following describes the check where the receiving computer sends back a copy of the data to the sending computer to allow it to compare the data?

• echo check

• checksum

• ARQ

• check digit

Which of these is not part of the header:

• Packet Number

• Protocol

• Receiver IP address

• Data

An extra bit added to a string of binary code to ensure the number of 1-bits are either even or odd, depending on the system used:

• ARQ

• Checksum

• Parity Check

• Check Digit

The final number in a code of numbers. It is calculated from all the other numbers in the code. It’s purpose is to spot errors on data entry

• ARQ

• Checksum

• Parity Check

• Check Digit

A type of encryption that uses public keys and private keys to ensure data is secure

• Symmetric

• Asymmetric

• Blowfish

• Advanced Encryption Standard

A method of checking transmitted data for errors; it makes use of acknowledgement and timeout to automatically request re-sending of data if the time interval before positive acknowledgement is too long

• Checksum

• Check Digit

• Automatic repeat request (ARQ)

• Echo Check

An additional digit appended to a number to check if the entered number is error-free; a data entry check and not a data transmission check

• Check Digit

• Parity Check

• Echo Check

• Checksum