When I write a blog post, like this one, Your Blog, And Its Dual Personality, it has a known URL - http://bloggerstatusforrealbeta.blogspot.com/
2007/01/your-blog-and-its-dual-personality.html. It also has a second URL - http://www.bloggerstatusforrealbeta.blogspot.com/
2007/01/your-blog-and-its-dual-personality.html. Try the two links, and see for yourself.
(Note): This post has been replaced by (and substantially rewritten, to reflect major changes to the custom domain product) The Real Blogger Status: Schizophrenia and Custom Domain URLs. You may also find insight in The Real Blogger Status: Your Browser Cache, and Web Sites With Dual Addresses
That's real, but it's not terribly useful. I advertise this post as http://bloggerstatusforrealbeta.blogspot.com/
2007/01/your-blog-and-its-dual-personality.html, not as http://www.bloggerstatusforrealbeta.blogspot.com/
2007/01/your-blog-and-its-dual-personality.html, intentionally. This blog is "bloggerstatusforrealbeta.blogspot.com" - "www.bloggerstatusforrealbeta.blogspot.com" is not necessary.
But what if this blog was "bloggerstatusforrealbeta.com"? That would make this post http://bloggerstatusforrealbeta.com/
2007/01/your-blog-and-its-dual-personality.html. If properly setup, it should also be addressed as http://www.bloggerstatusforrealbeta.com/
(Note): Since I haven't setup a domain "bloggerstatusforrealbeta.com", don't expect to click on any of the latter links, and get anything useful. Sorry.
The point here is that "bloggerstatusforrealbeta.com" and "www.bloggerstatusforrealbeta.com" should be synonymous - for a domain that only contains a blog. For other domains, this may vary.
For many domains, the "www" prefix will be synonymous with the root - but not for Google Custom Domains.
- I pay for the DNS listing, which tells your computer where my blog is.
- I setup a DNS entry, pointing "bloggerstatusforrealbeta.com" to "ghs.google.com".
- I setup Blogger to publish to the custom domain.
From what I see, redirecting "bloggerstatusforrealbeta.com" to a web site on a Google server involves two address records.
- A CNAME record at my DNS service, forwarding "bloggerstatusforrealbeta.com" to "ghs.google.com".
- A pointer at "ghs.google.com", forwarding "bloggerstatusforrealbeta.com" to the actual physical website.
Google hosts lots of blogs, so we have to make sure the right one is associated with this domain.
My guess is, when I tell Blogger to publish my blog to "bloggerstatusforrealbeta.com", and to host the content on their server, they do three things:
1) Create the content, with links using "bloggerstatusforrealbeta.com" as the base URL.
2) Copy the content to the web server, in the proper location.
3) Create a pointer, on "ghs.google.com", indicating where the content was copied.
The result is that I have a pointer indicating the location of "bloggerstatusforrealbeta.com". I'd bet that also setting up a pointer for "www.bloggerstatusforrealbeta.com", indicating the same location, was a detail that Blogger overlooked.
The bottom line? I can setup a pair of CNAME records in my DNS service, both pointing to "ghs.google.com" - "bloggerstatusforrealbeta.com" and "www.bloggerstatusforrealbeta.com". But, without a pointer on "ghs.google.com", indicating the server where "www.bloggerstatusforrealbeta.com" is located, I'm out of luck for addressing this post as http://www.bloggerstatusforrealbeta.com/
(Edit 1/15): Using "martinezumc.org" as a publishing target for "martinezumc.blogspot.com", I see complete agreement with the above.