There is a hot debates amongst SEOs about what type of redirects to use for SEO, specially when it comes to passing PageRank. If you use a 301, 302 or 307 redirect, is it matter? As we have seen sites use a variety of redirect styles, for whatever reason.
I recently saw someone trying to argue that the use of a 307 redirect was a blackhat spam technique, while many sites use a 302 when they clearly mean to use a 301. Google has also said it doesn’t matter whether you use a 301 or a 302 when switching to HTTPS, they will both pass PageRank to the new URLs (before, Google said there is lost around 15% of PageRank juice when 301 redirection), which makes sense since site owners would be reluctant to switch to HTTPS if there was the potential loss of PageRank from making a site more secure.
From my experiences so far, the “best practices” option is to use a 301 redirect when it is permanent. Sometimes website owners or the tech department use one of the other redirects (302 is the most common). But it won’t cause issues related to loss of PageRank by doing so.
In other hand, many webmasters would like to know more about the difference between a 301 and 302 redirect. To a user, they seem to work the same way. But not for search engines. Search engines sense the different types of redirects, and handle them differently. A 301 redirect means that the page has permanently moved to a new location. A 302 redirect means that the move is only temporary.
Search engines need to figure out whether to keep the old page. Alternatively, replace it with the one found at the new location. If the wrong type of redirect has been set up, search engines may become confused, resulting in a loss of traffic.
This is very important, for instance, if you are moving to new domain name. You want both your visitors and search engines to be able to find your site, and recognize that it is the same with the old site.
A redirect causes the user’s browser to automatically forward from the old location to the new one. That’s where things get complicated, even though you might think that Google and the other search engines would just follow the redirects. When a site moves, that can trigger the Google aging delay. Usually the site drops out of the search rankings for several months, sometimes even a year. We’ll come back to this later.
Google recognizes that many people use 302 when they really mean 301. Fortunately, Google isn’t bound by any law to take people literally. For the sake of producing the best possible search results, Google can and probably can figure out that the webmaster really means 301, when they do 302. But depend on Google is not clever.
Whether Google actually handles 302s properly is still an open question. If a 302 is used instead of a 301, search engines might continue to index the old URL, and disregard the new one as a duplicate. Link popularity might be divided between the two urls, hurting search rankings significantly.
As long as you create a 301 redirect when you indeed want to permanent redirect, it is the correct way. And it shouldn’t be an issue in the long run. Perhaps there still a lost 15% of PageRank, but through the time, the site might be back to normal again.
As long as you can avoid 404 errors (a.k.a page not found) from happening at any time, that should reduce the risk greatly. It’s when a page changes and a good link goes to a 404 that you will run into ranking issues.