When you have a number of domain names with different extensions and you need all of them to open the same website, you could have the website under one of them and forward the others. There are a number of approaches to forward one domain name to another, like the so-called domain parking. When your web hosting plan allows it, though, it will be better if you host all of the domains and create a URL redirect, not a domain redirect. The real difference between the two is that while a domain name is hosted, you could still have content for it, set up subdomains, e-mail addresses, and many others., while with a parked domain you cannot do any of these things. As an illustration, if you're building localized Internet sites under various country-code Internet domain names, you will be able to work on them, but in the meantime, people shall be redirected to the primary website.