In Exercise 4 php section my marks are deducted because my alert messages are different.

Question

I used different alerts other than alert(document.domain) it was not mentioned in question.

Answer 1

The requirement for the alert is mentioned in the description for Task 2:

Task 2: XSS Pentest
You are now hired as a penetration tester! Either find a working payload to automatically execute alert(document.domain) when the page is opened […]