Is it necessary to move the site with forwarding?
JOHN MEULLER (Webmaster Analyst from Google):
Yes, definitely make sure that you’re using redirects from the old version to the new version. We have a relatively new part in our help center about moving sites, about changing hosting, for example. And I’d definitely go through that so that you understand what we recommend and see how far you can actually go there. If you’re just moving the site from one server to another and you’re keeping the same URLs, then of course we won’t see any 404s because the URL will just be active on the other server. The only thing you need to watch out for is that there is this kind of overlapping time between the time when we recognize that this URL is hosted somewhere else and the time that we still have your old IP address essentially cached. And during that time, it probably makes sense to have the content available on both of these servers so that users and our crawlers don’t get stuck there. But if you’re moving from one domain to another, definitely make sure you set up the redirects so that we can kind of pick up on that connection and that we don’t have to guess at what’s actually happening here.