Earlier this year, Google’s Gary Illyes stated that 30x redirects (301, 302, etc.) do not result in a loss or dilution of PageRank.
As you can imagine, many SEOs have greeted this claim with skepticism.
In a recent Webmaster Central Office Hours Hangout, I asked Google’s John Mueller whether perhaps the skepticism was because when SEOs experience loss of visibility during migrations, they might not realize that all signals impacting rankings haven’t passed to the new pages yet, so they assume that PageRank was lost.
Yeah, I mean, any time you do a bigger change on your website — if you redirect a lot of URLs, if you go from one domain to another, if you change your site structure — then all of that does take time for things to settle down.
So, we can follow that pretty quickly, we can definitely forward the signals there, but that doesn’t mean it will happen from one day to the next.
During a migration, Googlebot needs to collect huge amounts of data for collation in logs, mapping and updated internally, and rankings can fluctuate throughout this process.
But in addition to that, when Googlebot visits plays a fundamental part in rankings fluctuation during a migration, and that can relate to “URL scheduling,” a key component of crawl budget.
Crawl budget = host load + URL scheduling combined
URL scheduling is essentially “What does Googlebot want to visit (URLs), and how often?” Host load, on the other hand, is based around “What can Googlebot visit from an IP/host, based on capacity and server resources?” Together, these make up “crawl budget” for an IP or host.
Both of these still matter in migrations.
On a 10-page brochure site, you likely won’t see any loss of visibility during a site migration.
But what if your site is, for example, an e-commerce or news site with tens of thousands, hundreds of thousands, or more URLs?
Or what if you’re merging several sites into one on the same IP host?
For everything to be fully passed, it all has to start as a bare minimum with at least a complete site crawl by Googlebot.
It may even take a few complete site crawls, as Googlebot understands more about URLs — and how everything fits and links together internally in a site — with each subsequent visit to a newly migrated site.
On larger sites, that may not happen as soon as you’d hoped.
You’ve likely spidered your website with your favorite crawling tools prior to migration “go live,” and you’re confident that there are no issues.
But then rankings and overall visibility drops. What could have gone wrong?