I'm developping a multi-tenant web application in ASP.NET MVC and it will provide my users the ability to have a custom subdomain pointing to their account page (like user.myapp.com). I already have it working by using a wildcard DNS entry and a code to query the database to load the user data based on the domain.

I'm planning to offer the possibility of using custom domains, allowing the users to buy their own domains and use it instead of the subdomains that will be provided by default.

I currently use DNSMadeEasy to host the DNS for the application main domain.

I just don't know what kind of settings I must make to allow this feature to work, since the users will have domains hosted in several companies. Will I have to create my own nameservers and provide it to my users?

What other things I must consider to implement it efficiently?