How to create this type of subdomain on the fly like Blogger.com

Question

Sometime ago I asked this question and I was told that the entry has to be made in DNS etc. I was not sure whether all this is really required or not. The kind of feature that I am looking for is shown in the screenshot below:

As you can see blogger lets the user choose the subdomain for his blog. How can we achieve this? I am basically developing in asp.net C#. How can I allow my users to choose subdomains like this once I have my top level domain. Currently I am developing on localhost.

Genocide

Answer 1

Use a wild card domain in IIS so it traps every request to the top level domain and under.

In asp.net: Create an HttpModule... this will run for every request and you can check the domain name, etc and pull in user information based on the sub-domain. An example httpmodule can be found at URL Rewriting in ASP.NET via HttpModule.

In asp.net mvc: Create a custom RouteHandler (custom based on interface IRouteHandler). Look at RouteHandler vs ControllerFactory question for an example.

Coop

How do I add wildcard DNS Mapping in IIS 7.5? The article I am referring is http://www.purpleant.com/Blogs/BrianSwanson/tabid/64/EntryId/144/Wildcard-sub-domain-for-Microsoft-IIS-and-DNS.aspx but this is of IIS 6. How can I do it in IIS 7.5? – Genocide

learn.iis.net/page.aspx/508/… – Coop

It can also be done without writing an HttpModule by using IIS UrlRewrite 2.0. You setup the format of your url in the web.config and then you can access that value via the querystring. – Canny

Sadly the first link seems to be dead, getting 404 error. – Theaterintheround

Yes, it appears that link is dead. But fear not - MS has information on that as well: msdn.microsoft.com/en-us/library/bb398986.aspx – Coop

Answer 2

You need to add a wildcard DNS mapping that maps *.example.com to your webserver, and a wildcard hostname mapping telling IIS to send all subdomains to your ASP.Net website.

You can then check Request.Hostname in server-side code and use the appropriate content (or error message)

Ludwog

How do I add wildcard DNS Mapping in IIS 7.5? The article I am referring is http://www.purpleant.com/Blogs/BrianSwanson/tabid/64/EntryId/144/Wildcard-sub-domain-for-Microsoft-IIS-and-DNS.aspx but this is of IIS 6. How can I do it in IIS 7.5? – Genocide