A "scenario" is a concrete situation - include a summary of the purpose of A, the purpose of B, and the reason they need to communicate A few scenarios are so obvious that they require no imagination, and therefore ARE NOT ALLOWED: in your http scenarios, neither A nor B can be a web browser in your http scenarios, neither A nor B can be a web server in your smtp scenarios, neither A nor B can be an email server Your reasons for recommending each protocol should comprehensible, and after reading them, I should agree that you have a point, but you do NOT have to convince me. It's OK if I disagree with you, as long as your arguments are reasonable. There's no fixed requirement on the length of this paper, but 3-4 pages should be enough. To get full credit, you only need one good scenario of each type; providing two scenarios instead of one will increase your chances of having at least one good one.