Computing an Internet checksum
Consider the two 16-bit words (shown in binary) below. Recall that to compute the Internet checksum of a set of 16-bit words, we compute the one's complement sum [1] of the two words. That is, we add the two numbers together, making sure that any carry into the 17th bit of this initial sum is added back into the 1's place of the resulting sum); we then take the one's complement of the result. Compute the Internet checksum value for these two 16-bit words:
00010110 00011111 this binary number is 5663 decimal (base 10)
10100000 01101011 this binary number is 41067 decimal (base 10)
Question List
1. What is the sum of these two 16 bit numbers? Don't put any spaces in your answer
2. Using the sum from question 1, what is the checksum? Don't put any spaces in your answer
Solution
1. The sum of 00010110 00011111 and 10100000 01101011 = 10110110 10001010
2. The internet checksum is the one's complement of the sum: 10110110 10001010 = 01001001 01110101
That's incorrect
That's correct
The answer was: 10110110 10001010
The answer was: 01001001 01110101