If you have several domain names with different extensions and you need all of them to open precisely the same site, you may have the website under one of them and forward the rest. There are a number of methods to forward one Internet domain name to another, such as the so-called domain parking. If your web hosting package deal permits it, though, it'll be better if you host all the domains and create a URL redirect, not a domain redirect. The real difference between the two is that while a domain is hosted, you can still have content for it, create subdomains, email addresses, etc., while with a parked domain it's not possible to do any of these things. As an illustration, if you are building localized sites under different country-code Internet domain names, you will be able to work on them, but meanwhile, people shall be redirected to the main site.