I’m posting this as a quick reference on how to use the Alternate Access Mapping in WSSv3 and MOSS 2007.
Alternate Access Mapping enables you to access your Sharepoint site via a typical url like http://mysharepoint.com instead of hitting the server name at http://mysharepointserver. In combination with DNS A host entries you can also define urls like http://mysite.mysharepoint.com even though your My Site web application is hosted on a different port.
So to start:
1. Go to Central Administration for your WSS or MOSS instance.
2. Click on the Operations Tab
3. Click on Alternate Access Mappings under Global Configuration
4. You should now see a list of your web applications, switch over to the one you want to map to the new URL by selecting it from the drop down on the right side.
5. Click on Edit Public URLs and change the desired zone URL type to your new domain name. You can also change your internal URLs also by clicking Add Internal URLs.
6. Now you’ll have to switch over to your DNS server.
Within the DNS Management Console and Under Forward Lookup Zones:
7. Add a new Primary Zone with your new domain name.
8. Add a new Host (A) to the records and point the IP Address to the sharepoint server.
And that should be it! Now you can have friendly URLs pointing to whatever Sharepoint Site Collection/Web Application you’d like without exposing the server names or ports.