Diagnosing Problems With Custom Domains - Case Study #6

In my previous custom domain case study, I presented a poorly working custom domain, where the "www" alias was properly setup, but the primary domain was using URL forwarding. Maybe it's a setup recommended by the DNS host technical support staff, who don't support "CNAME" referral for the primary domain.

Some DNS hosts just don't understand "CNAME" referrals, and the previous case doesn't show how badly domains can be setup.

Let's look at one case, again 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. 3600 IN A 64.202.189.170


Next, the "www" alias "www.mydomain.com".
;; QUESTION SECTION:
;www.mydomain.com. IN A

;; ANSWER SECTION:
www.mydomain.com. 3600 IN CNAME mydomain.com.
mydomain.com. 3600 IN A 64.202.189.170


And examine "64.202.189.170".
pwfwd-v01.prod.mesa1.secureserver.net (64.202.189.170)
64.202.160.0 - 64.202.191.255
GoDaddy.com, Inc.


The latter is using URL forwarding, to redirect "mydomain.com" to "myblog.blogspot.com", plus using a "CNAME" referral to direct "www.mydomain.com" to "mydomain.com" (and the URL forwarding). URL forwarding is preferred by some DNS hosts, who prefer to not to provide "CNAME" referral, but it's wrong when used in a custom domain setup. For Google Custom Domains, it will probably work, for a while, but unreliably so. Even if it works for a while, it will potentially cause problems, for everybody.

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