Yup. I have tested it. and it sends the mail if correct IP is provided.
But I want to test the validation for that filed.
I mean if you provide any incorrect public ip address and press the "submit" button, it provides message box on the screen with error.
While it is not providing the error message when I enter any incorrect Private IP Address, Say 184.108.40.206 (172.16.0.0 - 172.31.255.255). I just want to know, The Validation for the Private IP should also be implemented or not.
That question needs to be referred back to your application sponsor. No one on this site that doesn't work for your company on the same application can answer that question.
If your requirements/specifications say it should be implemented, then it needs to be there. If there isn't a definite non-ambiguous description of the functionality, then you need to ask for clarification and have the documents updated.
Insanity: doing the same thing over and over again and expecting different results