ADTRAN interview question

You have two eggs and a 100 story building. These eggs are identical and possibly much harder than normal eggs. Your goal is to determine the highest floor of the building they can be dropped from without breaking using the fewest test drops. What is the optimal search algorithm? How many drops would it take using the algorithm in the worst case scenario? NOTE: Once an egg breaks, it can not be used again for further test drops. NOTE 2: This is an "inside the box" riddle, no tricks.