I have a website hosted at Amazon S3; the URL is something like www.foobar.com.s3-website-us-east-1.amazonaws.com. I would like to set my domain registrar (Name
You cannot serve "domain apex" content from S3-hosted websites. The easiest solution is to configure your domain such that "foobar.com" is redirected to "www.foobar.com". Unfortunately this requires you to run a HTTP server with a rewrite rule to enforce it.
I can't vouch personally for the service but http://www.wwwizer.com/ offers a free apex to www redirect service.