If you have a few domain names with different extensions and you need all of them to open the very same website, you may have the website under one of them and forward all the rest. There are a number of methods to forward one domain to another, like the so-called domain parking. When your 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 name is hosted, you can still have content for it, create subdomains, email addresses, and so on., while with a parked domain you are unable to do any of these things. For instance, if you are building localized websites under different country-code Internet domain names, you'll be able to work on them, but meanwhile, people will be forwarded to the main website.