domain / exchange question…

I have a customer network where they are hosting their own domain’s email using MS Exchange. Let’s say the domain, for example’s sake, is “example.com” and all the domain user’s email addresses end in “@example.com”. They also have a website that is named “www.example.com”. If they were unable to view or ping their website from inside the domain what could the possible isues be?

I can supply addition info if needed.