at is a cache? In your past projects, what types of caches were present?How would you decide if you should buy servers with more memory or disk space?...

What is a cache? In your past projects, what types of caches were present?How would you decide if you should buy servers with more memory or disk space? How would you develop a cost model to help you make the decision? // This question is probably best for someone with some experience managing or having exposure to servers. You can still answer it without that knowledge of course, but there may be better questions.