I am overtaking a large site and wanted to know is it necessary that I register the site as DBA (Doing Business As) for under my business name which is totally different from the site name? I heard some people run large sites for years and have a different business name and never register a DBA under their business name.
The answer to your question is that it depends on where you are located.
Some U.S. states require DBA registration and some do not.
The idea of behind requiring a DBA registration is to provide transparancy to the public about who owns a business. Whether you are required to file a DBA registration in your jurisdiction or not, I would certainly make it clear who owns the business in the TOS and/or the "contact us" portion of your site.