So let’s go to the whiteboard a little bit. There’s a bunch of different ways to diagram what a site looks like. One common one at Google is to diagram a site like this. Because you’ve got your URL structure, and then you can have a subdirectory underneath that. And so you can have individual pages on the site, all that sort of thing. So let’s talk a little bit about 301 redirects. The most common case for a 301 redirect is you’re moving from one site to another site. And if you’re doing that, you can put 301 redirects to go to the root of the new domain. But that’s kind of a waste.
If somebody is looking for a very specific page, and they end up going to the root page of the new domain, that’s really not as useful. So what we recommend doing is doing a 301 redirect from the old page location to the new page location on the new site. And so the question is about whether there’s a limit to that. Can you do too many 301 redirects? What if I’ve got 100,000 pages on my site? Is there some cap that says I can’t do a 100,000 301 redirects? And the answer is no.
So that’s kind of helpful to know. We’ll look at as many pages as we’re willing to crawl on the old domain. And if we see a 301 redirect, then we’ll put that in the queue to crawl at the new location, and we’ll process that. Now just as a reminder, 301 redirects, or permanent redirects, should only be used when you’re truly migrating for all time in eternity. You’re not ever coming back. If it’s going to be temporary or you might undo it after a while, that’s a good opportunity to use a 302, or a temporary redirect.
So you’ve got your 301 redirects. It’s totally fine to do it from every page. In fact, it’s better to do it from every page to the corresponding new page on the new site. There’s no limit on the number of 301 redirects that we’re willing to crawl within a site. But there is one limit that you should know about. Suppose you start on one page and you do a 301 redirect to another page, and then you do a 301 redirect to another page, and then, you can see what’s coming, you do a 301 redirect to another page and another page. At what point does Googlebot sort of stop and get busy and say, you know what? I’m done following redirects. If you can do it in one hop, that’s ideal. Right? Because then you don’t have to worry about people getting lost. The latency is much lower. All that sort of stuff.
But we are willing to follow multiple hops, multiple levels of redirects. At the same time, if you get too many, if you’re getting up to the four or five hops, then that’s starting to get a little bit dangerous, in the sense that Google might decide not to follow all of those redirects. So there’s no limit per page or per site. There’s no limit per site on the number of permanent 301 redirects that we’ll follow.
So if you can keep that down to one or two, maybe three, that’s much better. Once you get five or six redirects in a row, in a chain, the odds are very, very low, close to zero, that Googlebot would actually follow all of those redirect hops to get to the new destination. So that’s just a very quick overview of how it works. I hope that explains things relatively well. And if can do those redirects to do the granularity of page level to page level, that’s a great user experience. And the page rank and those sorts of things should flow relatively well to the new site as well. And so everything should go pretty smoothly. Thanks very much.
by Matt Cutts - Google's Head of Search Quality Team