In a form to be filled out by a user, the application should use the following principles to avoid missing data or submitting wrong values.
Whenever an object is created or edited, always differentiate the required fields from optional.
If a text field has some restrictions on input data, place a corresponding comment below the field.
All user-entered data must be validated in the browser before the user submits it for further processing.
The following example shows explicitly that only the Description field is optional and that the required Server Name field is still empty: