In case you have several domains with different extensions and you need all of them to open exactly the same site, you can have the website under one of them and forward the rest. There are several approaches to forward one domain name to another, like the so-called domain parking. If your website hosting package allows it, though, it'll 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 is hosted, you could still have content for it, create subdomains, e mail addresses, and so forth., while with a parked domain you cannot do any of these things. As an illustration, if you're building localized sites under several country-code Internet domain names, you'll be able to work on them, but in the meantime, visitors shall be forwarded to the primary site.