MATT CUTTS: Hi everybody.
It's Matt Cutts.
We're back for another round of Webmaster
questions and answers.
At this point, we have made over 375
videos to answer questions.
So we started to say, well maybe we should act a little
bit like Princess Bride and go back to the beginning and do a
little more tutorial sort of informative videos to sort of
make sure the people understand all of the really
important things that matter, but that are also sometimes a
little more basic rather than just a random question that
somebody asks that we're doing a one or two minute answer.
So I wanted to talk a little bit about 301 redirects today.
The question is one that I typed in myself.
And it's, is there a limit to how many 301 or permanent
redirects I can do on a site?
How about how many redirects I can chain together?
OK.
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.
Right?
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.
There's no queue There's no cap.
There's no limit that says, OK, we are only going to look
at 10,000 301 redirects from one site to another site.
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.
OK.
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.
However, there is a limit in the sheer number of chain of
redirect hops that we are willing to 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.