You will want the naked and www subdomains to point to the same address in your DNS configuration, and you will want to configure your webserver to issue a 301 redirect to the canonical subdomain at the HTTP layer. There are several reasons for this, but the most pressing is that it does not make sense to use a CNAME record for the naked domain.

If you have a larger setup, you’d want to already serve the 301 on your load balancer.

There's a slight advantage to doing it at the registrar because it keeps the hit off your servers. This is assuming of course that http://foo.com/bar will get redirected to http://www.foo.com/bar rather than just having everything redirected to the http://www.foo.com.

Edit: I'm wrong. See tadfisher's comment below.

Note that the usual method for doing so (a CNAME on the bare domain) prevents you from adding other resource records (such as MX) on the domain.

1. http://joshstrange.com/why-its-a-bad-idea-to-put-a-cname-rec...

That's interesting. Currently I have 2 different domains at 2 different registrars. In each case I have the bare name, www and other subdomains as "A" records, not CNAME.

So it doesn't matter if people use the www prefix or not, since both point to the same IP. And with this configuration I've had no trouble with MX records.

If the goal is www/no-www transparency, there are other ways to do it, but using a simple DNS setup seems like the least hassle.

The main reason to redirect to one or the other is to have a canonical URL scheme for search engines.

Great point. And candidly I never actually do this myself (CNAME on the bare domain), I just point it at the server and let apache/nginx handle the redirect.

Yes, this is the problem at my registrar if I setup a redirect there. Everything gets redirected to www.foo.com instead of www.foo.com/bar.