subdomains vs. Google

Hi, i have got to understand something and would really appreciate help on this.
I read the instructions on this site and also on others on how to set joomla mobile, on some guides it is recommended to set a subdomain but not redirect to mobile.yoursite.com and when i access this site via iphone it is using the domain site url aka: www.mobilejoomla.com/ not a subdomain.
Currently i set up the site with redirect to iphone.mysite.com and kept the rest (pda,imod ect..) not using subdomains.
What is the best approche google wise? if using a subdomain do i have to redirect or uncheck the redirect option? (doesn't make sense because it will not use the subdomain url right?)
If i don't redirect can google see the site as duplicate? same question if i redirect to subdomain, is this a risk of being duplicate?

I hope i made myself clear...thanks.
The site is Cole instruments hair transplant devices

Please....anyone?

Google has both "desktop" crawler and few mobile ones. And it seems reasonable to redirect each of crawler to corresponding subdomain if such exists (to prevent indexing of the same page on both domain and subdomain).

Thank you
So you recommend setting the sub domains for all types (pdf, iphone,ect..) with "Redirect to domain" checked on the joomlamobile settings right?...i am left with a question:
why is this site not doing sub-domains? it should set as an example...by not redirecting to subdomain as you said they are risking in google duplicating their site right?
When i accessed this site via iphone it didn't take me to a subdomain

ronyeli wrote:
It's not necessary. The question here is: what link would you like to get by using google search on mobile device?

ronyeli wrote:

We had subdomains but seems forgot to renew it after one of servers updates.

ronyeli wrote:

No. If you have no subdomains, there is no need to redirect, of course.

[quote="dryabov" post=4248]ronyeli wrote:

Can you please elaborate a little on this?...you mean that when there is no subdomain my site with not be searchable by google mobile? can you explain on the difference?

Google uses special crawlers and index for mobile websites (this index is used at www.google.com/m/). So, there is two possible situations:

1. You don't use subdomains at all. In this case MJ will correctly determine type of the crawler and show corresponding content to it. As a result, there is no duplicating content per crawler.

2. You use subdomain(s) for different site version(s). In this case mobile crawlers will be correctly redirected to the subdomain, but there is a chance that general crawler will start to index subdomain too. Google is able to determine type of website on the basis of http headers and DTD markup type, but to prevent indexing for sure, I'd recommend to use the following substitution in .htaccess:

with corresponding m.robots.txt:

It will prevent general google bot (with "Googlebot/" in User-agent string) from indexing the subdomain, but allows to do it by mobile crawler (with "Googlebot-Mobile/" in UA).

Also I'd recommend to replace in modules/mod_mj_markupchooser/tmpl/default.php

by

(but anyway google isn't able to visit this links correctly because it doesn't support cookies, and anyway indexing of subdomain is disabled in m.robots.txt).

Thank you.
So what is the advantage of using subdomain?...if it's only for the mobile search then i will drop it because it's not important for me
Is it only for mobile search?

ronyeli wrote:

Using of subdomain is the best way to say your users that you have special optimized mobile version of the site (otherwise it's unclear). Also you can use name of the subdomain for marketing purposes.

I think Google has a different crawler for mobile and for desktop sites. They are aware of mobile websites and so I think they know how to separate one from the other. But hey, that's one question I have never heard before.