Which layer abstract away the need for any other layers to care about what hardware is in use?

When running anti-virus software , what could be a reason where recipitent is not guaranteed that data being streamed will not get interrupted?

Create a class named majors that includes an enumeration for the six majors offered by a college as follows: acc, chem, cis, eng, his, phys. display the enumeration values for the user, then prompt the user to enter a major. display the college division in which the major falls. acc and cis are in the business division, chem and phys are in the science division, and eng and his are in the humanities division. save the file as majors.java.

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?