Domain Migration – An SEO Case Study

Imagine the moment: Your client calls to let you know they’ll be changing their domain name, and that they need an SEO strategy to maintain their SEO visibility. Now imagine that particular client happens to be in a high competition niche: car loans. It’s the kind of thought that can keep you awake at night!

We’ve recently survived a domain migration project covering exactly the situation above. A high competition market, with a subdomain to full domain migration. That’s “*.domain.co.uk” to “www.newdomain.co.uk”. With the very kind permission of the client in question, I’m going to share the methodology we used.
Charting visibility



The first and most important step in any SEO project is to start collecting data, early. I’m a big fan of the search engine visibility metric as an aggregate measure of the health and performance of a website. This chart shows a daily search engine visibility percentage for the old domain. Don’t panic about the drop in visibility! That was intentional. To get this data we use Advanced Web Ranking, collecting ranking data for both the old and new domain names.

The keywords selected are the top 100 highest traffic driving terms in Google.co.uk. For a migration, monitoring terms already driving traffic to the site seems much wiser than the more aspirational “industry top terms” that we monitor visibility on an ordinary SEO project.
Visibility (Old vs New)



This chart, with it’s daily update (7am, every morning for the last month – the first email I’ve checked every day!) shows what’s been going on. The green line is the new domain visibility – though the chart doesn’t show it, the new domain actually outranks the old by a few tenths of a percentage. The symmetry is amazing, in the past 30 days I’ve found this chart to be so fascinating.

You’re viewing this correctly: No drop in visbility using a site wide 301 redirect to a new domain.
Plan your migration

Before you make any changes, it’s wise to create a domain migration plan. We created a step by step, timeline of events with checks and conditions that should be met before progressing to the next stage. The plan was researched (it’s been a long time since I read Google Webmaster documentation so closely!), documented and discussed with the clients. Given their pivotal role in all of this, we quickly built a close working relationship with our clients and made sure the plan was understood by all parties involved.
Think about the variables

When a domain changes, what are the variables? What are the flags that might tell a search engine that something huge has changed? What if such a thing as a “bait and switch” filter exists that could catch us out with a perfectly legitimate domain change? There were more questions raised than this, but you can probably see an insight into my thought process while the migration plan was being hatched.

If you understand all of the variables, you can plan to change them one variable at a time. It’s variables that can make or break a domain migration. In my opinion, these are the most important:

- Old and New domain WHOIS details
- Host IP
- Content
- Most “powerful” links by PageRank and mozRank
- Highest traffic driving links

We decided to try and change as few variables at any one time through the process. If anything went wrong we’d have a fighting chance at identifying the cause of the issue and resolving it quickly.
A step by step overview

Broadly speaking, we planned to change the domain first, making sure the host IP, WHOIS and content all remained unchanged. As a group we agreed to review changes in visibility daily and watch closely for changes. Here’s a step by step breakdown of what we did at the point of migration:

- Kept site content exactly the same (more on this later)
- Matched the WHOIS to be exactly the same as the old domain
- Kept the host IP stayed the same
- Created a sitemap xml file at the same URL on both domains
- Submitted the old sitemap file a few weeks before transition
- Submitted the new XML sitemap file as soon as the domain went live
- Pinged Bing and Google with the old sitemap XML file URLs, being sure that the old sitemaps would respond with a 301 redirect to the new files
Link realignment

We’d prepared a list of the highest traffic driving links prior to the migration. This list also included high PageRank / mozRank links too. We’d made contact with as many webmasters linking to the site as possible, informing them that we were going to change the domain over in the near future. This made the actual changes a lot smoother, and webmasters were informed when the domain swapped over (and were asked very politely to change the links over!).
Webmaster Tools – Change of address



To my surprise, there is no change of address feature for subdomains in Google Webmaster Tools. If you’re writing a migration plan involving a subdomain redirection, don’t count on Webmaster Tools for help. Why Google have taken this option I really don’t know.
The final step – content

Part of the project was to launch a new website. We deliberately decided to hold on the content changes until the domain had migrated smoothly. Prior to the new site going live, we meticulously crawled the site using a URL list created from the original domain. Checking that each URL responded with a redirect and ultimately took our crawler to the appropriate page, we launched the new site with a sense that errors would be kept to a minimum, and the redirects would continue to do their work.
Post migration thoughts

The process went smoothly, much to everyone’s relief. A domain migration is not to be taken lightly, and planning your steps can help relieve some of the worry that your site could lose its rankings. With that said, all the planning in the world still needs a little luck to help things run without a hitch.

For me, I found the symetry in the visibility shift amazing. There was a moment (for about 2 hours last weekend) where both domains ranked quite well. It was almost as if two indexes were being merged into one, a potentially fascinating insight into Google’s index consolidation and management process. I’m glad we’ve been through this migration, and I’m actually really grateful for Google’s level of documentation on the topic. So few SEO blogs have a decent guide to the subject, it’s quite alarming!