create the root site collection upon a Web application with the URL
http://intranet.companyname.com, instead of the original :
1. Confirm that http://:81 has been created successfully and the root site collection is accessible.
2. In Central Administration, switch to Application Management page, select Create or extend Web applications, and then Extend an existing Web application.
3. In the next page, please fill the following key blanks: Web Application: http://:81/ Create a new web site: Port: 80 Host Header: intranet.companyname.com Load Balance URL: intranet.companyname.com:80 Zone: Intranet Click OK to finish the configurations. You can confirm if the extended Web application is correctly added by going to Alternate Access Mappings page of Operations page under Central Administration site.
4. On the DNS server of your Active Directory domain, add the following DNS entry in the Forward Lookup Zones called "companyname.com": New Alias (CNAME) Alias Name: intranet FQDN for target host: .companyname.com
5. Empty the DNS cache in a test client (ipconfig /flushdns) and try to access the site via http://intranet.companyname.com
Apply host headers You can apply host headers at two different levels: The Web application (IIS Web site) level The site collection level In most cases, applying a host header at the Web application level makes it impossible to access host-named site collections. This is because IIS will not respond to requests with host names that differ from the setting in IIS. However, you can access host-named site collections if you configure the IIS Web site of the Default zone without a host header, and only apply host headers to the IIS Web sites in the other zones. This allows you to use the Default zone with host-named site collections, which are considered to be in the Default zone, while allowing you to use alternate access mapping functionality in the other zones for path-based site collections. To apply host headers at the Web application (IIS Web site) level: 1.Click Start, point to All Programs, then point to Microsoft Office Server, and then click SharePoint 3.0 Central Administration. 2.On the Central Administration home page, click Application Management. 3.On the Application Management page, in the SharePoint Web Application Management section, click Create or extend Web application. 4.On the Create or Extend Web Application page, in the Adding a SharePoint Web Application section, click Create a new Web application. 5.On the Create New Web Application page, in the IIS Web Site section, configure the host headers for your new Web application by typing the URL you want to use to access the Web application in the Host Header box. The host header value specifies the binding to create for the IIS Web site and ensures that IIS only responds to requests sent to the specified host header. You can manually modify IIS bindings from the IIS Manager, but this is not recommended. Any changes you make using the IIS Manager will not affect Office SharePoint Server 2007. If Office SharePoint Server 2007 tries to provision an IIS Web site on another computer in the farm for the same Web application and zone, the binding specified on the Create New Web Application page is used. If you want to modify an existing binding for an IIS Web site, remove the Web application from the zone and then re-extend the Web application into the zone with the binding you want to use. Configure a host-named site collection Office SharePoint Server 2007 ships with a set of Web services for various user and administrative tasks. One of these administrative tasks is creating a new site. The CreateSite Web method does not support the creation of host-named site collections. A workaround for this issue is to write a Web service that wraps the API sample code. There are several additional configuration options to consider when provisioning a new Office SharePoint Server 2007 site. Specifying the appropriate site template during site creation will determine which preconfigured Web Parts and other user interface elements are available on the new site. In a hosting scenario, you will probably want to select either a team site template (value of “STS#0” when creating the site) or a blank site with no Web Parts or prebuilt lists (value of “STS#1”). In a hosting environment, consider specifying site quotas on each newly provisioned Office SharePoint Server 2007 Web site. Although support for site quota templates is not included in the sample Web services, you can add site quotas and use them to create a site quota template based on predetermined limits. Create a host-named site collection using SQL authentication Working with the SQL membership provider in a hosting scenario requires some additional steps to properly configure and manage a host-named site collection. When you create any site, you need to specify a user who will be the site owner. This implies that the owner already exists as a user in your membership directory. To simplify this and other SQL membership provider tasks, use the MembershipSiteAdmin.exe tool.
see: http://technet.microsoft.com/en-us/library/cc424952.aspx http://www.toddklindt.com/blog/Lists/Posts/Post.aspx?ID=39 http://www.tech-faq.com/understanding-host-name-resolution.shtml http://www.infopathdev.com/blogs/janice/archive/2009/02/16/sharepoint-host-headers.aspx http://vspug.com/spfromscratch/2008/02/28/alternate-access-mappings-in-server-farm/ http://blogs.developpeur.org/themit/archive/2006/11/28/sharepoint-2007-host-header-mode.aspx http://technet.microsoft.com/en-us/library/cc262778.aspx http://technet.microsoft.com/en-us/library/cc424952.aspx http://blogs.technet.com/josebda/archive/2006/11/07/installing-rtm.aspx http://www.sharepointdiy.com/tutorials/ie-7-login-prompt-after-installing-moss http://blogs.msdn.com/sharepoint/archive/2007/03/19/what-every-sharepoint-administrator-needs-to-know-about-alternate-access-mappings-part-2-of-3.aspx http://blogs.msdn.com/sharepoint/archive/2007/03/06/what-every-sharepoint-administrator-needs-to-know-about-alternate-access-mappings-part-1.aspx http://books.google.ch/books?id=UnwBAmgvQ3oC&pg=PA343&lpg=PA343&dq=dns+host+a+sharepoint&source=bl&ots=5wTs_k6fkW&sig=fe6tA8XeagbMF1TCtyK2NMBS_1Y&hl=fr&ei=DxBDS6iYBMGksAaotsGgAQ&sa=X&oi=book_result&ct=result&resnum=8&ved=0CDAQ6AEwBzgU#v=onepage&q=dns%20host%20a%20sharepoint&f=false http://dhruvshahsp.blogspot.com/2009/03/host-headers.html https://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.public.sharepoint.portalserver&tid=0f001896-1815-421f-8453-caca6abc6579&mid=11ef1ef0-1148-4ec1-bcb5-0b71c00bbdde&cat=&lang=&cr=&sloc=&p=2 http://support.citrix.com/proddocs/index.jsp?topic=/access-gateway-91/agee-client-connect-cvpn-sharepoint-dns-resolution-tsk.html http://technet.microsoft.com/en-us/library/bb727005.aspx http://www.c-sharpcorner.com/UploadFile/rifaqats/AlternateAccessMappings05052009050512AM/AlternateAccessMappings.aspx http://www.eggheadcafe.com/software/aspnet/30213632/change-web-site-url-name.aspx http://certcities.com/editorial/columns/story.asp?EditorialsID=370 http://vspug.com/andynoon/2007/07/04/defining-multiple-authentication-providers-to-a-single-moss-2007-web-application/ http://vspug.com/andynoon/2007/07/04/defining-multiple-authentication-providers-to-a-single-moss-2007-web-application/