SEO Tip #137: When I Change Domains How Long Should I Leave the Redirects In Place?
Matt Cutts: This is something where search engines can change their policies over time because we might see the web evolving or we might see how webmasters have issues or those sorts of things. I can tell you about my experience from moving MattCutts.com to Dullest.com and then Dullest.com back to MattCutts.com.
Whenever I decided to move back I used a 301 redirect and it took a period of several weeks because remember 301’s happen at a page level. So just because you see one 301 on one page of the old domain does not mean the entire domain has completely migrated.
What I did was set up the redirects such that every single page was redirecting from Dullest.com to MattCutts.com so it had been a complete transition. I really didn’t bother to check on Dullest.com for a few weeks, maybe a couple of months and then when I went back and looked at Google Analytics at that point all of my traffic had swapped over from Dullest.com to MattCutts.com.
So typically over a period of a few weeks, or several weeks, think about it like a couple months for example then we might be able to detect that a site has entirely moved. But if we’re getting mixed signals like some pages return a 200, which is an okay while other pages return a permanent or 301 redirect then we really don’t know what to make of that.
I’ve certainly seen some situations recently where a site had said I moved from olddomain.com to newdomain.com but they forgot to do a sub-domain and so they were still serving 200’s on the old sub-domain.
So it’s definitely not the case where you can assume everything will automatically and magically work perfectly. We do have a tool in Google Webmaster Tools where you can say, “My site has moved from here to here.” So you can do that, put the 301’s on each page level but I wouldn’t just assume it only has to be crawled once. Really Googlebot and Google need to build up enough confidence to really know that a site has fully migrated from the old site to the new site. So it can take a little while but hopefully after a while we do pick up on that.