From what I have read, the OP wants to build a full end-to-end ERP system so customers can buy web hosting and a domain and have the two automatically linked together.
This would involve a multi-step process:
- Become an ICANN (or country-specific) registrar and register with the appropriate registry to be allowed to do this. Then get their API (I'm guessing they're gonna be using something like SOAP, XMLRPC or some other kind of server-side XML transfer).
- When your customer registers a domain, the domain has to be registered on your nameservers. Set up a nameserver with your domain (contact your registrar and ask for "glue" records - you'll need a server with 2 Internet-accessible IPs for this).
- Read here for the innards of the Microsoft DNS API. This will tell you how to utilise the DNS WMI Provider (using dnsapi.dll) to query and manipulate DNS records via WMI on Windows 2000 and later.
Once you've done this, you're at a stage where your customer can register a domain via your website (which then gets registered with the registry via that XML call) and then the DNS records are added to your nameservers (so the domain actually points somewhere).
Then, you want to take that domain, and read up on Microsoft's IIS API so you can set up a new website with host header mappings that match the domain that's just been registered, along with setting up new subfolders and adding the domain to mail server software so you can also provide email.
In a nutshell, that's the programmatic process for a web app that sells web hosting, domains and email.
Hope this helps.
codegecko :-)