IT420 HW 3

Assume odd parity. The single-bit parity for the data 01101011 is

• 0

• 1

• 00010100

• Cannot be determined

A receiver receives a message containing redundant bits for error checking and uses those bits to determine that no error has occurred. What does the receiver then do with the redundant bits?

• discards them

• passes them to the next layer up in the network model at the receiver

• saves them for future use

• returns them to the sender

Can single-bit parity detect an error that flips exactly two data bits?

• No

• Yes

• Sometimes - it depends on the data

The checksum for 1000 bytes of data is 16 bits long. Assuming the same checksum algorithm is used, how long will the checksum be for 500 bytes of data?

• 500 bits

• 16 bits

• 8 bits

• cannot be determined

A CRC is 5 bits long. How long is the divisor?

• 5 bits

• 6 bits

• 7 bits

• cannot be determined

Assume 4-bit wide units of data. Calculate the checksum for 1101 1001

• 0111

• 0101

• 1 0 0 0

• 1010

Assume a bit sequence of 10110 and a divisor of 1001.

Generate the CRC

• 100

• 001

• 101

Assume a bit sequence of 10110 and a divisor of 1001.

Check the CRC

• checks, since remainder is 0

• does not check, since remainder is not 0

A CRC polynomial is x2 + 1. What is the divisor?

A CRC divisor is 1011001. What is the polynomial?