When you have a few domains with different extensions and you need all of them to open precisely the same website, you could have the site under one of them and redirect the rest. There are a number of ways to forward one domain to another, such as the so-called domain parking. When your hosting package deal permits it, though, it shall be better if you host each of the domains and create a URL redirect, not a domain redirect. The main difference between the two is that while a domain address is hosted, you could still have content for it, set up subdomains, e mail addresses, and so on., while with a parked domain you cannot do any of these things. As an illustration, if you are building localized websites under various country-code Internet domain names, you'll be able to work on them, but meanwhile, visitors shall be redirected to the primary Internet site.