Monday, October 13, 2008

Custom Domains And URL Forwarding - Still A Bad Idea

Setting up a Google Custom Domain, which gives us the ability to publish our Blogger blog to a non BlogSpot URL, is a reasonably simple process. That simple process, though, depends upon several not so simple factors.
  1. Our understanding of how rigidly simple the DNS setup is.
  2. Our acceptance of how rigidly simple the DNS setup is.
  3. Our use of a registrar that provides us the DNS setup that is required.
Custom Domain setup is simple, but allows for no deviations. You may read my series Diagnosing Problems With Custom Domains, and examine a total of 7 unique configurations, 2 of which work properly, and 5 which either don't work at all, or work temporarily or unreliably.

One example of the latter possibility - a configuration which works temporarily - is a custom domain setup using URL forwarding. Here, I'll show excerpted Dig logs of various domain DNS configurations.

During the past couple weeks, we have seen dozens of reports similar to "ronpaulnews.net".
ronpaulnews.net.        51      IN      A       66.249.81.121
www.ronpaulnews.net. 43200 IN CNAME ronpaulnews.net.

An intriguing variation would be "herotherlife.com".
herotherlife.com. 10800 IN A 74.208.41.41
www.herotherlife.com. 86400 IN A 72.14.207.121

Then, we have "reputationist.info".
reputationist.info. 3600 IN A 64.202.189.170
www.reputationist.info. 3600 IN CNAME ghs.google.com.

These are, each, various examples of URL forwarding. Apparently, URL forwarding worked for a while, though I've been predicting the emergence of this problem for some time. Now, changes by Blogger means that URL forwarding does not work reliably, and many blogs are out of action.

If your blog recently stopped working, and your DNS is setup similar to "herotherlife.com", "reputationist.info", or "ronpaulnews.net", that is why you are here. You need to change your setup to use a Google Apps configuration, with up to date DNS.

With a normal custom domain DNS configuration, the domain uses an "A" or "CNAME" referral, which points directly to a Google server. When the Blogger script verifies that the domain URLs both point to Google, it can proceed with confidence.

If one, or both, of the domain URLs point to a non-Google server
ronpaulnews.net.        51      IN      A       66.249.81.121
www.ronpaulnews.net. 43200 IN CNAME ronpaulnews.net.

or
herotherlife.com. 10800 IN A 74.208.41.41
www.herotherlife.com. 86400 IN A 72.14.207.121

or
reputationist.info. 3600 IN A 64.202.189.170
www.reputationist.info. 3600 IN CNAME ghs.google.com.

the Blogger script has no way of knowing that your Blogger blog is targeted, even indirectly. The Blogger script can't look within the forwarding script on the non-Google server, as it can when verifying "A" and "CNAME" referrals, by using Dig (as we do above). Trying to eliminate one cause of the "Not Found Error 404", the Blogger script is conservative, and without an "A" or "CNAME" referral, you see
Another blog is already hosted at this address.


It's quite simple, when you understand the complexities. But you do need to either understand the complexities, or at least understand that they exist, and accept the advice of the people who do understand.

Having changed your DNS to use "A" / "CNAME" referrals for both URLs, remember to publish back to BlogSpot, then republish to your "www" alias, to ensure a clean repair of the problem.

(Update 11/21): Want to see a tangible example why URL Forwarding is a bad idea? That's one more example showing that URL forwarding is simply another spurious solution.

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1 comment:

imamnic said...

Dear Chuck,
Thank you for the DNS analysis you did to my page
It's awesome, I am still learning on that

I am using URL forwarding because Blogger said if we use custom domain for other registrar but still using blogger as host, the picture will not be normal.
Of course I want my domain showed in address bar (like www.imamwahyudi.com, not redirected to imamnic.blogspot.com) but if that sacrifies the picture setting that would not be nice.
1. Is it true that if we assign CNAME using other domain registrar Blogger will not show our picture?
2. Can I renew my domain in blogspot with autenthication code from my last registrar (I switch the registrar not the domain)?

Thank you very much, your help is very much appreciated