Monday, December 17, 2007

Hosting Multiple Web Sites on a Single Server

More than 87% of active domain names are found to share their IP addresses (i.e. their web servers) with one or more additional domains, and more than two third of active
domain names share their addresses with fifty or more additional domains. While this IP sharing is typically transparent to ordinary users, it causes complications for those who seek to filter the Internet, restrict users' ability to access certain controversial content on the basis of the IP address used to host that content. With so many sites sharing IP addresses, IP-based filtering efforts are bound to produce "overblocking" -- accidental and often unanticipated denial of access to web sites that abide by the stated filtering rules.

A single IIS server can host multiple web sites and normally each web site is tied to a IP address however if the machine only has one IP address it can still be configured to host multiple web sites by specifying a host header name for each web site as follows (you should first ensure you have multiple DNS entries all pointing to the IP address of the machine):
1)Start the Internet Information Services MMC snap-in (Start - Programs - Administrative Tools - Internet Information Services)
2)Expand the server
3)Right click on the web site and select Properties
4)Next to the IP address (ensuring the actual IP address is selected) click the Advanced button
5)Select the IP address entry and click Edit
6)Enter the DNS host entry for the web site and set the port to 80
7) Click OK Click OK to the main dialog
8)Repeat for all other web sites
9)When the client connects the DNS name requested is passed in the header as the host name and that is what is mapped.
If the Web site requested in the host header is stopped, the client receives the default Web site. Therefore, it is recommended that an ISP use the default Web site as the ISP home page, rather than for a customer site. Multiple sites on a single Professional installation is not supported.
Also do not configure a header host name for the default web site as this may cause problems for other packages such as Proxy Server which expect the default web site to use port 80, IP address of "All Unassigned" and no host header name.

What is the difference between a static IP number and a Shared IP number

A Static IP Address is when a website has their very own IP Address. This means that whether you type in your URL or the IP address of your website, both will bring you to the same page.

Shared IP Address - Every web server around the world is assigned an Internet Protocol (IP) address. An example of an IP address would look something like: [126.703.4.151]. Most websites on the world wide web are hosted on shared IP addresses, meaning that one server with one IP address can hold several domain names.A shared IP Address is when multiple websites all share the same IP Address. In this case, the web server does a little bit of extra work when it receives your web request, and passes you to the correct website. Typing in the IP Address will not bring you to your desired website, under most conditions. Why do we need this? I’m sure you noticed that, based on the above definition of an IP Address, that there is a finite number of IP Addresses available before we run out completely. If every single website on the internet had it’s own IP Address, there would be no room for any new ones.
Back to our home address analogy, you might consider a static IP Address to be a stand-alone home. There is only one house who gets mail at that address. You might then consider a shared IP Address to be an apartment building. Many different households get their mail at the same location, and in turn it is distributed to the correct location.