Laks has posted a very good summary on how to implement host header mapping for authoring and production in the newsgroup which I would like to share with all of you:
I had gone through some trouble in figuring out this need. With help from stefans notes and microsoft support, i have put this together...
Taking CMS sites live through "Map Channels to Host Header names"
Typical testing of CMS websites in development environment is as follows:
Obviously this is not the way we can go live with. The production URL will have to be www.abc.com for the above scenario. Since the coding is done and tested for the first scenario, often when you take your site live, you will end up with a lot of broken urls etc.
This document is intended to simulate a test environment that will behave like your actual production and authoring sites.
Of the several ways that can be used to take a CMS site live, this is just one method.
Under the assumption that the production architecture is such that both the Production and Authoring will share the same database.
Have two web servers.
WS1 = Read Only ( Production )
Both the web servers point to the same database on DB1 server. The Database can be set using the DCA of Microsoft Content Management Server.
SCA setting can be done through any site. Set a value of Yes to "Map Channels to Host Header names".
Open a case with Microsoft to get hot fix for id 824597. This hot fix can be obtained only through opening a case with Microsoft.
(824597 - Absolute URL is returned when you use the channel.URL method of the API and Host headers are enabled)
Install the hot fix on the Authoring Server. Also download the ISAPI_Rewrite Lite (freeware) from http://www.isapirewrite.com . This can be downloaded for free. Install ISAPIrewrite on the authoring server.
Make the following entry on your hosts file on the production(WS1) web server. Hosts file is found on C:\Windows\System32\drivers\etc\hosts.
The initial portion is the IP address of the production(WS1) server. You can get the IP of the server by typing "ipconfig" on the command prompt of the machine or by pinging the server by its name.
Perform an "iisreset".
The production url works fine now. How will the authoring work. Map channels has been enabled, but that does not mean the publishers can access the same site to do publishing. You have to be able to distinguish between Authoring site and Production site.
Let us set up the authoring site.
Open the file in notepad and add the following lines of code towards the end of the file
RewriteCond Host: authoring\.def\.com
RewriteCond Host: authoring\.abc\.co\.uk
Perform an "iisreset".
For the actual production server the hosts file is not modified.
In addition to the hints from Laks above you need to take care of some other things when you are planning to implement host header mapping with authoring and production server or when you are planning to place the production or authoring server behind a publishing proxy server. In these situations the MCMS server will most likely be hit with a different host name when the request is forwarded from the proxy server than the host name the user entered in the browser (e.g. the netbios name rather than the DNS name or a DNS name that meets the domain name structure of the internal network.
In this situation you need to disable the <base> tag rendered by the RobotMetaTag control by either removing the RobotMetaTag control or by adding the following statement to the Page_Load event of each template if you would like to preserve the other features of this control:
RobotMetaTag1.RenderBaseHref = false;
If the MCMS server machine is published through a proxy server then you need also ensure that the hotfix mentioned above is also installed on the production server machines and not only on the authoring machine for the same reason.
824597 - Absolute URL is returned when you use the channel.URL method of the API and Host headers are enabled