Does Google treat subdomains as extensions of the main site (TLD) or is it considered a new site? Would SEO done on the top level site apply to all subdomains?
Google perceives all domain as a separate site, so zzz.domain.com and domain.com is seen as two different entities by Google.
SEO done on TLD does not apply on subdomains though. But when Google spiders start to 'hate' a certain domain, they would do the same for its subdomain. For example free subdomain like co.cc is partially blacklisted by Google because of spam. So when domain.com and domain.co.cc points to the same site, Google would rank domain.com higher. Purely because its a TLD and Google 'hatred' for co.cc
