quote:I want to set up a rule that says: 255.255.0.0 includes all IP addresses from X.X.0.0 to X.X.255.255 is allowed.
You seem to have mixed that up. Don't you mean 0.0.255.255, not 255.255.0.0? Or did you mean you want IP addresses from 0.0.X.X to 255.255.X.X? Your first value as the 255s in the front but your rule has the 255s at the end. Which is it?
The input mask is not what determines the rules by which the field abides. That falls upon the property Validation Rule.
Assuming what I said about 0.0.255.255, set up your field to be type DOUBLE. Set the input mask as you already set it. Then for Validation Rule, enter:
>= 0 And <= 255255
Michigan Dept. of Environmental Quality, Air Quality Division