CMS SCA Host Headers Mapping vs IIS HTTP Host Headers Mapping

MCMS Server Configuration Application (SCA) has an option to map channel names to host headers names. It can be used to allow host multiple CMS web sites with different domain names on the same CMS server.
To do this, we need to map top-level channels as the root channels for a URL with a host header name that is identical to the channel name. When CMS generates a URL pointing to an item inside the virtual site www.CMSsite1.com, it prefixes the URL with the name of the channels in which it is contained.’ See chapter 18 of book Microsoft Content Management Server 2002
There are two points need to note:
1. Names of top channels on a CMS server must match the virtual site names in IIS.
2. The virtual site names must be valid DNS name.

So a typical co-hosting configuration for three web applications on a development box can be:

In MCMS Site Manager:
We have three top channels, they sharing the same CMS database, and named as:
www.CMSsite1.com
-------------Product
-------------Service
www.CMSsite2.com
-------------AboutUs
-------------OnlineShopping
www.CMSsite3.com
…

Install a network loopback adapter and assign IP address from 192.168.2.1- 192.168.2.3

In IIS Manger, create three web applications named and assign IP address as:
www.CMSsite1.com (192.168.2.1)
www.CMSsite2.com (192.168.2.2)
www.CMSsite3.com (192.168.2.3)

Open %Winnt%\system32\drivers\etc\host with notepad and add following entries:
192.168.2.1 www.CMSsite1.com
192.168.2.2 www.CMSsite2.com
192.168.2.3 www.CMSsite3.com

So you may ask how will this related to HTTP host header mapping in IIS?
Not a lot. IIS HTTP host header mapping is used to provide multiple-hosting. The HTTP host headers identify multiple virtual web sites that reside on one physical server and all sites shares same IP address.
However, you need to configure the HTPP host headers on the IIS site if a single IP address is used for multiple CMS sites.