301 Moved Permanently: How to Use It Correctly for SEO

"301 Moved Permanently" is one of the server-side redirects and is an integral part of HTTP/1.1 (Hypertext Transfer Protocol). A complete description of the protocol can be found at ftp://ftp.rfc-editor.org/in-notes/rfc2616.txt, and "301 Moved Permanently" is covered in paragraph 10.3.2.

"The requested resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs." In other words, the page has been permanently relocated to a new location. How should the search engine spiders treat the pages that have been redirected to a new URI using 301 Moved Permanently? What information can we SEO's pass to the engines using the 301 HTTP response and how can we do it properly to avoid unnecessary complications?

301 and the engines

The engines read the 301 redirect like this: "Hey look, the page has been moved, and all the content we could find here before is going to be found over there! We should rank the page at its new location as we used to rank it at the old one, and all other parameters – link authority, PR and other derivatives – should be transferred to that new page, as well." In an ideal world, they would have done so immediately; in reality, while Google is very good at processing 301, Yahoo! still experiences technical difficulties. Even Google loses some 301-related information at times of major updates, and then the SERP's get filled with non-existent pages and URL's But it doesn't mean that we shouldn't use 301. We should. Apart from everything else, we shouldn't forget that it improves the users' experience when browsing sites; but while the users with their browsers won't see much difference between 301, 302 and the client-side meta-refresh redirect, the difference is huge for the engines.

Why 301?

Failure to use 301 to redirect a page from the old location to the new may result in great complications, such as a huge downward leap in search engine rankings, various penalties or 302 hijacking. First of all, if you use a JavaScript redirect or a client-side meta-refresh redirect, the engines can come to the mistaken conclusion that you are using doorway pages. The point is, these client-side redirects are often used by doorway creators to feed one version of a page to SE spiders and another one to the visitors with ordinary browsers. There is a lot of conflicting information on how the engines treat the meta-refresh (some say it can get a site banned, and others say that the engines will just treat them like 301 or 302), but it is widely agreed that if you use JavaScript-based redirects, the engines might definitely misunderstand your intentions. Why run the risk?

Even if they don't treat your pages as doorways, you will lose the chance to correctly transfer the authority of the old page to its new location.

The 302 (Found) redirect, meaning that the page has been temporarily moved to the new location, is also quite dangerous. It doesn't transfer the link popularity and other authority factors to the new location of the page, as the engines assume the page will be returned to the old location after a certain period of time. What's more, if you allow 302 to sit too long on your domains, the sites will lose whatever Google rankings they ever had. I have seen the results of improperly used 302 that had spent a year in place; those results were disastrous to the site owner. Replacing 302 with 301 worked to some extent, but the initial damage was so big and penetrated so deeply that many more months could still be needed to restore the pre-302 level of Google-generated organic traffic.

Besides, some cases of the inappropriate use of 302 may result in the so-called 302-hijacking (a separate issue outside of the scope of this article). It is therefore not recommended to use it at all, unless you are 100% sure you know what you are doing.

301 is the safest method of redirecting old locations of pages to new ones. It won't cause a penalty (with 301, all user-agents see the same version of the page, so it is not deceptive at all), and sooner or later it will be correctly processed by all engines and help the site owners solve a lot of tasks that would otherwise have been impossible to solve.

When we use 301

The commonest function of the 301 redirect, which all site owners need these days, is the redirect from the "non-www" version of the site's URL to the "www" one (for example, http://mydomain.com/ to http://www.mydomain.com/). It is a must these days, as it helps prevent the 302 hijacking, merges the overall link popularity of both versions of the URL and prevents the duplicate content filter, which the engines apply at times to such domains, when the redirect is not in place. Many site owners still neglect the issue, and as their websites still do fine in the engines, they think it won't do them any harm if they just let the issue go. Others have never heard about the issue at all. But in certain cases, the absence of such a redirect leads to terrible consequences, and anyway, prevention is better than cure.

Another common case of using the 301 redirect is the multi-domain issue. It was a popular strategy during the formative years of the WWW to secure many different domains and load them with identical (or nearly identical) content in the hope of getting more traffic this way (or even increasing the link popularity of some of those domains). In those days it actually worked; now I'm hearing more and more often of the harm it does to the owners of such networks. Duplicate sites get filtered from the SERP's and if the owner is lucky, at least one of the sites will still rank and gather visitors; in the worst case they will all be booted, and thus the filter turns into a penalty. Even aliased domains (physically pointing to the same content) aren't safe any more.

The only way to handle the multi-domain issue safely and ethically is to 301-redirect all spare domains to one, main domain. That includes misspelled versions of the domain names, which everyone might want to secure, thus making sure that people who mistype the URL in their browsers will end up in the right place.

Here's another case. Let's say you moved a few articles from one of your websites to another one. A 301 redirect on a per page basis is recommended here. The same applies to completely redesigned websites, in case it is not possible to preserve all the URL's Closed projects, which you can't maintain any longer, should be 301'd to the main domain within your network to salvage at least some of the authority they have accumulated over the years, and to keep the visitors.

There are many other cases in which 301 will come to your rescue. All of them are considered white hat and ethical. But I would like to highlight some cases of unethical use of the 301 redirect.

Buying authority

Since the Google of the old days merged the authority of the domains pointing to the same location via 301, many SEO's started buying multiple high-PR domains and redirecting them to their (or the clients') main domains, thus increasing the overall authority of the target domain immensely and achieving very high rankings. This method was so highly abused that Google, it would appear, is taking just one of the domains in the group (the one with the highest authority), and giving its authority to the domain chosen as the main one. What's more, it doesn't happen at once. There is a certain time lag (usually about three months) before the authority transfer is completed and the original rankings are restored.

For this reason, if you have several domains you are going to merge using the 301 redirect, I would recommend pointing all domains to the one which has the most traffic, the highest Google PR and the best rankings across the three main search engines. This applies unless you have a special reason to promote another domain; in this case be prepared to wait a few months.

With Google's aging delay working, some SEO's figured out a way to beat it quickly by simply 301-redirecting a folder on their old, established domain to a new domain belonging to them or the client. In some specific cases it could be okay (when, for example, the folder has become so independent from the main site that it makes sense to create a separate resource out of it). But I wouldn't recommend it as a strategy, especially if you do SEO for clients.

First of all, if the content in the folder on your old domain has nothing to do with the site you are redirecting it to, it becomes somewhat deceptive, especially if the owner is different. Second, when you have achieved rankings for your client's site using the 301, how are you going to handle the situation when the contract is over? By removing the 301 and letting the rankings drop? Or by keeping it in place? Then how are you going to "refuel" your stock when you run short of folders? By keeping dozens of established domains online, each one filled with temporary content, "waiting" for their hour to come? Those will be dead sites existing for no purpose other than to be used one day and to make Google think that the new site is not new at all. In my book, that comes under the definition of SE spam.

Apart from the two cases mentioned above, I can't think of any other examples of the unethical use of the 301 redirect (which doesn't mean they don't exist). In many other cases, 301 is the best way to handle things.

How to do 301

You might want to ask me now how to practically establish the 301 redirect on your sites. I will give just one example, most often needed by webmasters. If you are on an Apache webserver, you can add the following code to your .htaccess file.

Options +FollowSymLinks
RewriteEngine on

RewriteCond %{HTTP_HOST} ^mydomain.com [NC]
RewriteRule ^(.*)$ http://www.mydomain.com/$1 [L,R=301]

This will redirect all pages within mydomain.com domain to the corresponding pages at www.mydomain.com.

For more information about the 301 redirect, its technical implementation and various cases of use, I would recommend the following sources:

Redirects Using Scripting for SEO's by Ian McAnerin
Redirecting URL's and Browsers – IIS by Chris Hirst

In both cases, it is a good idea to click on links you will find within those articles to find a wealth of good information.