The risk of identity theft is not as great, when you change a custom domain. You will continue to "own" any previously used domain, even when unpublished - but the risk of technical error is just as real.
If you care about blog accessibility, you will plan this process, with some care.
Changing one domain, for another, requires careful planning.
A domain change involves world wide services. Neither you, Blogger Support, or your registrar / DNS host can control this process. Domain setup needs to be carefully verified, over a significant time span.
- Register the new domain.
- Setup the new domain, with proper DNS addresses.
- Give the new domain time to stabilise.
- Click on the "X", and publish the blog back to BlogSpot.
- Change BlogSpot URL, if desired.
- Publish the blog to the new domain.
- Verify the blog, published to the new domain, is working.
- Re direct the old domain, to the new domain published URL.
- Publicise the new domain.
- Update any owner added internal links.
Register the new domain.
Choose a registrar who can provide the necessary services - such as email, if that's important to you.
A properly chosen registrar won't be free. You are unlikely to get a free domain, that will be reliable.
Setup the new domain, with proper DNS addresses.
Just as important as a reliable registrar is a proper address complement. You need a reliable registrar, for a dependable domain - but even a reliable registrar won't necessarily understand what DNS addresses are needed.
It's up to you, to ensure that your domain DNS addresses are properly setup. Nobody can do this, for you.
Give the new domain time to stabilise.
The DNS addresses need to propagate uniformly, through the worldwide DNS infrastructure. Having some computers able to access the domain, and others not, may lead to Google database corruption.
If the domain was used previously, you'll still have to wait - while any previous DNS addresses expire, from the many DNS servers, worldwide.
Click on the "X", and publish the blog back to BlogSpot.
If you wish to publish the blog to the new domain, it must be first published back to BlogSpot, using the Publishing wizard in the Blogger Settings - Basic dashboard page. Skipping this step may be another cause for database corruption.
Change BlogSpot URL, if desired.
Having prepared the new BlogSpot URL, now you swap the operational blog and stub blog URLs - if desired. This is the simple 1 - 2 - 3 swap that must be done in one uninterrupted 5 minute session, to reduce the risk of identity theft.
Publish the blog to the new domain.
Now, you see how well the DNS addresses are setup, and hope that the addresses have propagated uniformly. And be prepared to (possibly) verify domain ownership. This is what follows, when you click on the "X".
Verify the blog, published to the new domain, is working.
Test all 3 URLs - the BlogSpot URL, the domain root, and the "www" host - and ensure that all work. Use multiple browsers, multiple computers, and various online services.
Verify from multiple locations, using services like GeoPeeker, and What's My DNS. And do this over hours, if not days.
Be diligent and thorough, here - don't get caught, unaware, when your readers in another country contact you, complaining of the blog being offline.
Re direct the old domain, to the new domain published URL.
If you are retaining the old domain, at least temporarily, redirect it to the new published URL. This must be done from the DNS host, it's not a Blogger option.
If done properly, redirection from the old domain URL, to the new URL, will provide some initial search engine reputation, and traffic. This can't be done until the new URL is working - but should be started shortly afterwards.
Publicise the new domain.
As you did when you started the blog - and as when you published to the first custom domain, the blog needs to be re indexed under the new URL. Make the reputation of the new domain justify the effort involved in the above process.
Update any owner added internal links.
When you publish to a custom domain, all Blogger generated dynamic links - such as Archive and Label index gadgets, and Label links at the end of the posts - are updated, to point to the custom domain.
When you publish back to BlogSpot, all Blogger generated links are updated, to point back to the BlogSpot URL. When you publish to the new domain, the Blogger generated links are updated, to point to the new domain.
Owner added links are not updated, in either case. As when publishing from BlogSpot, all owner added links are the owners responsibility.