If you're redirecting based on user-agent or browser capabilities, then it is an inherently temporary redirect. You need visitors to land on your redirect URL so that you can ascertain which version to browse to.
A concrete example - if I emailed a link to a friend, would I prefer it to be the page that works out if I'm mobile or not, or a device-specific version? I don't know the technology that will be used, so I would prefer the former.
So for me, it's a 302 every time (possibly 307) which tells the user-agent to request the original URL.
Receptional Andy -
Just saw this post today on Google Webmsaster blog [googlewebmastercentral.blogspot.com ].
They are specifically recommending a 301 redirect from www.domain.com to m.domain.com.
So it appears the 'official' recommendation from Google is use a 301.
Yeah - I guess the argument here is that for that user-agent, the permanent location is the mobile version. Doesn't make good technical sense to me though. It also raises a few question about having a separate mobile and desktop search index - presumably that means an entirely different link map for mobile content.
Still, if Google says that's the way they want it, then serving googlebot-mobile a 301 is the way to go.
This is a good discussion - worth more attention, I'd say. My own feeling is that serving a mobile site on a dedicated hostname is not what the original W3C vision was. Their idea is to serve different CSS files based on the user-agent.
That would certainly make any redirect questions irrelevant. But I can't get past the idea that even with serving an appropriate CSS for mobile browser file, you'd still be serving a lot of unneeded code to a mobile browser. With mobile connectivity and bandwidth challenges very much with us, I'm still more comfortable with a dedicated hostname and a redirect.
Google assures us that a 301 redirect for mobile user agents is what they will deal with most effectively, and I haven't heard any contrary reports.
the john mu replies and link she provides in this google webmaster help forum thread should give some insight.
How does Google treat mobile sitemaps that are almost identical to standard desktop ones? - Webmaster Central Help:
i'm trying to find another source on this i read recently and if i do i'll post something.
301 works almost well. Dekstop version of Google won't list mobile URLs, and mobile version marks them as mobile-friendly. But WMT throws "When we tested a sample of URLs from your Sitemap, we found that some URLs redirect to other locations. HTTP Error: 301" for mobile sitemap.
|...and link she provides... |
*and links he provides as well*
Thanks for this guys. I've just been through a similar process with a client and upon checking it's currently using a 302 redirect. At present it doesn't seem to be having any detrimental effect but I'll ensure it's changed to a 301 to comply with Googles guidelines. Thanks for the link @Scott_Mc!
301 or 302, I asked Matt Cutts which to use at SMX West last month. He was not able to give me a clear answer at that time. He told me he would ask the question to the right team. But I'm sorry I have no idea how to get the answer from him. :(
I don't know how many times I have switched:
Originally a 302, then I switched to a 303 and now I am using a 301.
The 303 was showing the mobile version and desktop versions on the g search results together...definately not what I wanted.
We will see how the 301 works out.
Hopefully g can confirm which of the redirects is the way to go.
The link Scott_Mc offered in the third post is to a recent official Google blog article that recommends a 301 for mobile users who request the desktop version - that includes the googlebot-mobile crawler.
The article is from Feb 2011 - I'd consider that to be the current official word on the type of redirect. The technical challenge (and gray area) is recognizing all the mobile user-agents properly.
|The technical challenge (and gray area) is recognizing all the mobile user-agents properly. |
Agreed! If you do go down the 301 route (which I have reconsidered since my previous comment) you certainly need to ensure you do not accidentally 301 any non-mobile crawlers to the mobile domain/sub-domain! Identifying all mobile user agents if one hell of a task so if anyone has any ideas/resources please share!
I'm gonna stick with the 302 for the time being as it seems to be functioning adequately - "if it's not broken don't fix it" as they say! I'll check back with an update in a couple of weeks.