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Hi Armin, So glad the community could help you find the best possible use of your resources by weeding out ones that wouldn't be best. Good luck!

Yes, subdomains linking to your main domain do flow link juice. However, having the exact same content could be an issue unless you noindex it, which will result in no juice being passed to the root domain. I would take a different approach tho, as you said, it could take far more coding, but the results would be much better. Make the root domain accept canadians a free customers (don't know how you are going to pull this, ips, sources, etc), but this approach will get the link juice directly in your root domain instead of passing it through the subdomain and probably getting a penalty for duplicate content. Also, take into consideration that if Canadians get the service for free just from accessing from Canada, other users from other countries may just use a VPN (like HMA) to access the site and look like Canadian visitors... Hope that helps!

Thanks Martijn

Subdomains are basically different domains, so if your competitor does it a lot, and they interlink all those pages, they could even get a penalty. If you use subfolders, all the link juice you get to any page will affect the entire site, as opposed to subdomains, where each backlink affects the subdomain itself, and therefore the main domain gets less juice. Both are possible and accepted, but if you ask me, I would go with the sub-folders instead.

Actually I am not targeting Iran. My main market is the US and Canada but here are people who like to use a Farsi portal. So what I am planning to do is to have my English website(Primary one) like abc.com/lang:eng and then add a sub-directory for Farsi like abc.com/lang:far for the times users choose to switch the language to Farsi. Then I can use specific Farsi meta titles and description for my Farsi version of the website which obviously would be totally different than my English version. It is in a way the same way as the reference website you mentioned is doing.

Glad it helped. Feel free to mark the question as answered if you are satisfied with the response. Have a good one!