Interactive end-of-chapter exercises


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:


   10110100   00100010      this binary number is 46114 decimal (base 10)

   11001101   01001000      this binary number is 52552 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 10110100 00100010 and 11001101 01001000 = 10000001   01101011

2. The internet checksum is the one's complement of the sum: 10000001   01101011 = 01111110   10010100



That's incorrect

That's correct

The answer was: 10000001   01101011

Question 1 of 2

The answer was: 01111110   10010100

Question 2 of 2

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