Either of them will allow you to use IIS Express with Visual Studio.
To follow this guideline, you need to develop the ability to reason about the kinds of exceptions your code is likely to throw.
Declaring a function noexcept helps optimizers by reducing the number of alternative execution paths. The keyword noexcept serves two purposes (like most of the language, really): It's an instruction to the compiler, and it's also helpful to humans who are reading the code.
But the humans need to know that it has two different meanings: This guideline addresses the first meaning.
Here's what the guideline says: If your function may not throw, declare it noexcept.
My only issue with this guideline is the use of the word "may" because some people will interpret that as equivalent to "must not throw" or "is not allowed to throw" and others as equivalent to "might not throw." However, the Reason section of the guideline makes it clear that the first meaning is intended: If an exception is not supposed to be thrown, the program cannot be assumed to cope with the error and should be terminated as soon as possible.