IP Conflict

My Exchange Server keep returning same IP address with that of my website domain name when pinged. This has been preventing my Intranet email (Exchange/Outlook) configuration from working properly. My Outlook keeps displaying “Disconnected”. My LAN’s domain name is like “domain.com” and my website domain name is like “www.domain.com”. Can this similarity cause the problem? Apparently, the DNS is resolving the two entities to same IP address. How do I correct this, please?