Given the following object,
public class Question
{
[Required]
public string QuestionText { get; set; }
[Range(1, 5)]
public int Difficulty
Validator.TryValidatorObject(instance, validationContext, validationResults) calls Validator.TryValidateObject(instance, validationContext, validationResults, validateAllProperties) with validateAllProperties = false.
When validateAllProperties is false, only the RequiredAttribute will be validated.