Your question is Server Number Allocation. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Determine how to assign server numbers as requests for new servers are received. Be efficient with allocating and deallocating server numbers. There are different types of servers, and each type should have it's own set of server numbers that can be assigned