Which entries in the dos header are necessary?

Question

I am writing a PE generator, I need to know which entries in the DOS header section are necessary for execution on NT based systems.

I checked some exes on my drive and most entries in the DOS header are 0 but I am not sure if this is the norm.

Answer 1

On an NT system the loader just checks for the magic numbers at the beginning MZ / 0x4d 0x5a and then the member e_lfanew to get the NT header offset.