Matt Cutts: There is some loss of PageRank with 301 permanent redirect

[djbaxter]

Matt Cutts Interviewed by Eric Enge
Stone Temple Consulting
March 14, 2010

Eric Enge: Let?s talk a little bit about the impact on PageRank, crawling and indexing of some of the basic tools out there. Let?s start with our favorite 301 Redirects.

Matt Cutts: Typically, the 301 Redirect would pass PageRank. It can be a very useful tool to migrate between pages on a site, or even migrate between sites. Lots of people use it, and it seems to work relatively well, as its effects go into place pretty quickly. I used it myself when I tried going from mattcutts.com to dullest.com, and that transition went perfectly well. My own testing has shown that it's been pretty successful. In fact, if you do site:dullest.com right now, I don't get any pages. All the pages have migrated from dullest.com over to mattcutts.com. At least for me, the 301 does work the way that I would expect it to. All the pages of interest make it over to the new site if you are doing a page by page migration, so it can be a powerful tool in your arsenal.

Eric Enge: Let?s say you move from one domain to another and you write yourself a nice little statement that basically instructs the search engine and, any user agent on how to remap from one domain to the other. In a scenario like this, is there some loss in PageRank that can take place simply because the user who originally implemented a link to the site didn't link to it on the new domain?

Matt Cutts: That's a good question, and I am not 100 percent sure about the answer. I can certainly see how there could be some loss of PageRank. I am not 100 percent sure whether the crawling and indexing team has implemented that sort of natural PageRank decay, so I will have to go and check on that specific case. (Note: in a follow on email, Matt confirmed that this is in fact the case. There is some loss of PR through a 301).

There is a lot more of interest in this interview, including

• what determines Googlebot crawl rate and the number of pages crawled
• how does Google deal with affiliate links
• the effect of hosting and "host load"
• duplicate content and "wasted crawl budget"
• session IDs
• rel=canonical tags
• PDF files
• PageRank sculpting

Read the full article

 

[DrMarie]

Very interesting!

Why does Matt Cutts say not to use session ids?

 

[djbaxter]

If you use them for logged in members only, you're fine. But guests (which includes search engine spiders) shouldn't be getting them because that results in the same page having a large number of URLs, i.e., the actual link plus a session ID which changes from one "get" or "fetch" to the next -> which results in a big duplicate content issue.