The UDP 16-bit Internet checksum on the data can be disabled by setting the checksum field to:Question 19Select one:a.all 0 bitsb.-1c.0xffffd.65535

To determine how to disable the UDP 16-bit Internet checksum, let's analyze the options provided.

Breakdown of Each Option

1. a. all 0 bits
   If the checksum field is set to all 0 bits, the checksum would be treated as 0, which does not disable the checksum but indicates a non-functional checksum.

2. b. -1
   In many programming contexts, -1 is represented as the maximum value for an unsigned 16-bit integer, which is $0xFFFF$ or 65535. This is not a direct representation but is related.

3. c. 0xffff
   This option directly sets the checksum to its maximum value in hexadecimal. Setting the checksum to $0xFFFF$ effectively indicates that there is no valid checksum being calculated.

4. d. 65535
   This is the decimal equivalent of $0xFFFF$. Setting the checksum to its maximum value in decimal also effectively indicates that the checksum is not valid.

Analysis and Summary

The correct answer for disabling the UDP checksum must be one that nullifies its effect, and based on the definitions above, both $0xFFFF$ and 65535 are valid representations to achieve that.

Final Answer

The best option is c. 0xffff (which is equivalent to d. 65535, but the direct hexadecimal representation is more standard in this context).