Ping resolves indifferent server name

I manage a Windows NT Server which runs MS Exchange Server.

When I ping the IP address of the server with the -a option, the server name resolved is indifferent from what the actual server name is.

For eg., if my server name is: name.xyz.com, the resolved name is: server.xyz.com

Also what I could notice is that the Message-ID generated by the Exchange Server reflects the incorrect server name.

Any idea why these are happening?

Help greatly appreciated.

Thanks in advance