Redirecting web pages is one task that is very important to search engine optimization (SEO). All webmasters will eventually be called upon to implement redirects. So it is important for them to understand the only globally accepted SEO-friendly redirect in their arsenal – the 301 permanent redirect.
When is redirecting web pages necessary?
When a web page is deleted or moved to a new location (i.e. its URL is changed), it is almost always a good idea to implement a 301 Permanently Moved redirect. The 301 redirection will notify any browser or crawler requesting the old URL that it has been permanently moved as well as provide with the new location of the web page. This should be done for many reasons… some of which are SEO-related… some of which are usability-related.
One of the few situations when you might not want to implement a 301 redirect is if you delete a web page and you do not have another page on your site whose content even remotely resembles the content of the old page. But typically in this situation I’ll 301 redirect the old URL to my home page so that it at least benefits from the page rank being passed into the old URL via its inbound links.
Why is redirecting a web page important?
The most important asset that a web page has from an SEO perspective is its inbound links, especially those links from external sites. Inbound links from other sites can bring your site natural traffic as a result of users following links from other sites. Inbound links are also important to a URL’s rankings in the search engine results pages (SERPs).
A URL’s inbound links and their associated link text carry more weight than any other ranking factor in determining how a web page ranks for a particular keyword phrase. So a good webmaster will always try to maximize the SEO benefits gained from links pointing to their site. 301 redirecting old web pages which have been deleted or moved will insure that the inbound links to the old page are not wasted.
Redirecting web pages with a 301 redirect
When a web page is deleted or moved, the webmaster should implement a 301 permanently redirecting the web page’s old URL to a URL on the site whose content most closely resembles the content previously found at the old URL. By doing so they maximize the chance that the target web page will benefit from an SEO perspective since the link text of the old URL’s inbound links will likely be applicable to the content of the new page if they are similar.
The short-term effects of 301 redirects
When a URL has inbound links from other web sites and is ranking well in the SERPs, 301 redirecting that web page will almost always negatively affect rankings and the organic search traffic that those rankings generate in the short-term. If you understand how search engines deal with 301 redirects, you will understand why doing so will cause a site to take a hit to its rankings and traffic. The good news is that the drop in rankings and traffic should be temporary if the webmaster has done their job implementing the redirects correctly.
For example, imagine that a web page at URL A on your site has 1000 inbound links with many variations of “your targeted phrase” as the link text. Also assume that URL A ranks well for “your targeted phrase” and several slight variations of that phrase resulting in quite a bit of organic search traffic to the web page found at URL A.
Now assume that for whatever reason you need to move the page found at URL A to a new location at URL B. So you implement a 301 redirect for URL A to notify browsers and search engine crawlers that you have permanently moved the web page to URL B.
The next time the search engine crawls one of those 1000 inbound links and requests URL A from your web server, it will return an HTTP Status of 301 Moved Permanentlywith a Location value of URL B. This tells browsers and crawlers that the page they requested has been permanently moved and can now be found at URL B.
So the crawler will then request URL B. If your web server successfully serves up URL B and returns a 200 Ok HTTP Status then the search engine will transfer credit for that inbound link (and its associated link text) from URL A over to URL B. Now URL B has 1 inbound link that the search engine knows about.
Depending on the search engine, URL A might be immediately dropped from the index upon finding the first 301 redirect since it no longer exists (as is the case at Google) or the old URL A may simply now be seen as having 999 inbound links. Either way, as the inbound links to URL A are recrawled, credit for all of those links will transferred to URL B over time.
It is during this period when all of the inbound links to URL A are being recrawled, the 301 redirect is being discovered for each inbound link, and credit is being transferred to URL B for each inbound link that rankings and traffic will suffer. The good news is that if URL B is optimized to rank for the same keyword phrase as the old URL A then rankings and traffic should return once all inbound links to URL A have been recrawled.
How long it takes for your rankings and traffic to return depends on the crawl frequencies of the URLs that link to the old URL A. Some sites may get crawled daily while other sites linking to your web page might be crawled once every 4-6 weeks. So there is really not a lot you can do to speed up the process other than to be patient.
When can you stop redirecting web pages?
A lot of people have the misconception that redirecting web pages is only needed until all of the inbound links to the old URL have been recrawled and the new URL starts ranking. They think that once the rankings of the new URL return to the levels of the old URL that the 301 redirect can then be removed. This is not the case.
Once a 301 redirect is in place redirecting the web page at URL A to URL B, if you want URL B to continue to benefit from URL A’s inbound links then that 301 redirect must remain in place forever. If you remove the 301 redirect then the next time that the crawler requests URL A your web server will return a 404 Not Found HTTP Status telling the browser that the URL A web page doesn’t exist. If your server continues to return 404s for URL A for an extended period of time then URL B will begin losing credit for the inbound links to URL A. Rankings and traffic will likely plummet again.
If your web site is hosted on an Apache web server then I highly recommend familiarizing yourself with the basics of regular expressions and Mod Rewrite. The Mod Rewrite utility allows you to easily redirect web pages on your site using rewrite rules and conditions specified in .htaccess files. Once the .htaccess files are in place, you can actually delete the old web pages from your servers and the redirects will remain in place.
Redirecting web pages multiple times
Sometimes you will encounter situations where URL A has been 301 redirected to URL B for some period of time, but you now need to move URL B to URL C. One way to accomplish this is to simply 301 redirect all requests for URL B to URL C. However, this creates what is known as a stacked redirect. If a crawler requests URL A, it is redirected to URL B. When it requests URL B it is redirected to URL C. This daisy chaining or stacking of redirects is not optimal.
The optimal way to implement this is to un-stack the redirects. In other words, implement two separate redirects:
• 301 redirect requests for URL A to URL C
• 301 redirect requests for URL B to URL C
By implementing two redirects like the ones above, you avoid stacked redirects which can be a problem for some less sophisticated search engines.
It is also rumored that each redirect causes the inbound link to lose a small percentage of its “link juice”. So if there is any truth to this then being able to get to the final page in a single redirect will minimize the amount of “juice” lost to redirecting web pages.