If I have 20 domains, should I link them all together?

Matt's answer:

MATT CUTTS: Today’s question comes from South Africa. And the question is, “Should a customer with 20 domain names link it all together or not, and if he links it, should he add nofollow to the links not to pass PageRank?” So we were talking about this question before we started recording. And we said, well, first off, why do you have 20 domain names? If it’s all cheap online casinos or medical malpractice in Ohio, that sort of stuff, having 20 domain names there can look pretty spammy, and I probably would not link them all together. On the other hand, if you have 20 domain names and they’re all versions of your domain in different countries– google.co.za, google.fr, google.de, that sort of thing– then it can make a lot of sense to have some way to get from one version of the domain to a different version. But even then, I probably wouldn’t link all the domains, even in the footer, all by themselves because that’s a little bit strange. I’d probably have one link to a country locator page, which might even be like on the main dot-com, and you might have flags or something like that, so there are ways to get to those other domains. And as long as there’s a good way for users to get there, then search engines will be able to follow those links as well. Just make sure that they’re normal static HTML links, and we’ll be able to follow, and the PageRank will flow, and all that sort of thing. So if there’s a really good reason for users to do it, maybe you could have a drop-down, where you can pick your country or something like that. Then it might make sense. But having the country top-level domains is one of the only areas where I can think of where you’d really need to have 20 different domains. In theory, you might have a blog network. But even then, I’ve seen very large blog networks, and if you’ve got that footer at the bottom that has a lot of unrelated domains, at some point it gets pretty big. Even then, you’d probably only have like 10 domains and maybe a few posts on each domain that are linked to each other. So at the point where you’ve got 20, unless there’s a really good reason, I would be a little bit leery of just doing some massive cross-linking scheme between all of them.

by Matt Cutts - Google's Head of Search Quality Team

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