The best way to prepare for these exams is to keep up with the reading assignments and attend the class meetings during the semester. Then before each exam, you should review the material covered in the class (copies of slides used are available as class notes), referring to the reading material whenever necessary. For each exam there will also be a set of practice questions (exam1, exam2). You should make sure you have looked at these questions so that you know what to expect in the exam. In general, the questions will test understanding of the main concepts: the motivation behind problems and techniques, analysis of their successes and shortcomings, etc., rather than details of the algorithms and systems.
There will be no makeup exams without a valid proof of unexpected emergency.