Diagnosing Problems With Custom Domains - Case Study #4

In my first 2 custom domain case studies, I presented actual custom domains - all setup and working. Neither of those exemplify all custom domain setups though. In my 3rd post in this series, Diagnosing Problems With Custom Domains - Case Study #3, I showed a custom domain setup that was not only asymmetrical but incomplete. Here's a variation on that, where the primary domain isn't even defined in DNS.

Let's take a look at a fictional example "mydomain.com", setup using the "Advanced Settings" wizard.

There are 4 URLs to study here.

1. The primary domain "mydomain.com".
2. The "www" alias for the domain "www.mydomain.com".
3. The primary BlogSpot URL "myblog.blogspot.com".
4. The "www" alias for the BlogSpot URL "www.myblog.blogspot.com".

First, let's dig the DNS records for the primary domain "mydomain.com".

;; QUESTION SECTION:
;mydomain.com. IN A

;; ANSWER SECTION:
mydomain.com. 86400 IN SOA ns53.domaincontrol.com. dns.jomax.net. 2008032400 28800 7200 604800 86400

Next, the "www" alias "www.mydomain.com".

;; QUESTION SECTION:
;www.mydomain.com. IN A

;; ANSWER SECTION:
www.mydomain.com. 3600 IN CNAME ghs.google.com.
ghs.google.com. 586847 IN CNAME ghs.l.google.com.
ghs.l.google.com. 203 IN A 72.14.207.121

This is different from my previous case study.

mydomain.com. 3600 IN A 68.178.232.100
www.mydomain.com. 3600 IN CNAME ghs.google.com.

Here, only the "www" alias is defined at all - using a "CNAME". You should be able to publish to the "www" alias, but the primary domain just won't exist.

Now, let's look at browser connect logs. First, this is what we get for the primary domain "mydomain.com".

3/29/2008 08:50:42 Trying http://mydomain.com
Invalid Host

No DNS entry = "Invalid Host.

Next, the "www" alias "www.mydomain.com".

3/29/2008 08:50:17 Trying http://www.mydomain.com
Header:
HTTP/1.0 200 OK
Content-Type: text/html; charset=UTF-8

Here, we should see the content of the blog, simply labeled "www.mydomain.com".

Now, let's look at the BlogSpot URLs.

3/29/2008 08:56:48 Trying http://myblog.blogspot.com
Redirect!
Header:
HTTP/1.0 301 Moved Permanently
Location: http://www.mydomain.com/
Content-Type: text/html; charset=UTF-8

Here, we should see the same content as above, simply labeled "www.mydomain.com".

and

3/29/2008 08:56:38 Trying http://www.myblog.blogspot.com
Redirect!
Header:
HTTP/1.0 301 Moved Permanently
Location: http://www.mydomain.com/
Content-Type: text/html; charset=UTF-8

Here too, we should see the same content as immediately above, simply labeled "www.mydomain.com".

Both "myblog.blogspot.com" and "www.myblog.blogspot.com" redirect to "www.mydomain.com", again as in the previous study. Since no access to the blog, using the primary domain URL, is possible, this too is an incomplete result.

It's possible that proper DNS server configuration may transform an asymmetrical and incomplete scenario into an asymmetrical and complete one - that is - access to the blog through the primary domain URL.

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