Suppose that one byte in a buffer covered by the Internet checksum algorithm needs to be decremented (e. g., a header hop count field).
Give an algorithm to compute the revised checksum without rescanning the entire buffer. Your algorithm should consider whether the byte in question is low order or high order.
You can assume that you are given n the original checksum, the position of the byte which is to be decremented and the value by which the byte will be decremented.

Suppose you are an ad-serving company and you maintain a log of cookie data for ads you serve to the web pages for a particular vendor (say amazon). a. how can you use this data to determine which are the best ads? b. how can you use this data to determine which are the best ad formats? c. how could you records of past ads and ad clicks to determine which ads to send to a given ip address? d. how could you use this data to determine how well the technique you used in your answer to part c was working? e. how could you use this data to determine that a given ip address is used by more than one person? f. how does having this data give you a competitive advantage vis-à-vis other ad-serving companies?