In case you have several domain names with different extensions and you need all of them to open the exact same website, you can have the website under one of them and redirect the rest. There are several ways to forward one domain name to another, including the so-called domain parking. If your web hosting package allows it, though, it'll be better if you host each of the domains and set up a URL redirect, not a domain redirect. The difference between the two is that while a domain is hosted, you may still have content for it, create subdomains, e mail addresses, and so on., while with a parked domain you can't do any of these things. As an example, if you're building localized websites under several country-code Internet domain names, you'll be able to work on them, but at the same time, people shall be redirected to the main Internet site.