Matt Cutts via Buzz:
Let’s do another pass at the question “How does Google treat sites where all external links are no-follow?”
The short answer is that we don’t treat those sites any differently in our rankings, but it’s still not a good idea to do that, in my opinion. Here’s why. When Google sees a nofollow link we drop that link from the link graph we use in our web crawl: we don’t use that link to discover new web pages, and we don’t use the anchor text from that link in our scoring. … We changed the math several years ago so that if a link is nofollowed, that PageRank doesn’t go out on the other links instead [no sculpting]. — Read more
Related post found in this blog:
Links: No-Follow and Do-Follow
Matt Cutts tells SEOs ‘no more’ sculpting via nofollow
Say NO to Black Hat SEO
Thanks.
I found this video by Matt Cutts on nofollow, and the responses in the comments are interesting too.
How does Google treat sites where all external links are no-follow?
Hi David,
Yes the video and comments are interesting. I embedded that same video in this post Links no-follow and do-follow which is linked to in my “Related posts dound in this blog” in the post above.
When it comes to commenting on do-follow blogs, remember do-follow passes PageRank from the linking site to all the other links so if your are new to blogging
(a) your PageRank 0 zero blog doesn’t really benefit, and
(b) the more (spam/real) comments you get on a blog the less Page Rank there there is to allocate among the links out anyway.
The motivation for leaving quality comments on related blogs in your niche is to build authority.
Thank you for this and the link. I know that nofollow does not help, but I am not sure whether the absence of nofollow can actually hurts if the link out is to a ‘bad’ site.
Also, is the absence of a nofollow tag the same as the inclusion of a dofollow tag?
Do-follow comment links do pass on PageRank. No-follow comment links do NOT pass on PageRank. In the beginning all links were do-follow. However, it didn’t take long before blogs were being inundated by those who left insincere comments lacking in value just so they could get a backlink, so the original reason for the introduction of no-follow links was spam.
Without doubt linking to a bad neighborhood site can have a negative effect. Google Staff has made this clear for years now.
Different search engines interpret and treat no-follow and do-follow links in different ways.
No. WordPress, Blogger (Blogspot blogs), Typepad and most of the main blogging platforms have no-follow links enabled by default on comments and to change the links to do-follow links that pass PageRank action must be taken. So the implication is that each webmaster makes decisions about the links and the flow of PageRank.