ドメインオーソリティ(DA)
Domain Authority (DA) is a search engine ranking score (developed by Moz) that predicts how likely a website is to rank on SERPs. Based on factors like total backlinks and linking root domains, it ranges from 1-100. While not an official Google metric, it's the industry standard for measuring "trust."
Why International Structure Affects Authority
When expanding globally, your domain structure decision directly impacts DA. Using subdirectories (site.com/fr, site.com/de) keeps all authority on one domain—your French site inherits the DA of your main site immediately. Using subdomains (fr.site.com, de.site.com) splits authority—each subdomain starts at DA 1 and must build links independently. This is why most international SEO experts recommend subdirectories: they consolidate authority and enable faster rankings in new markets. The only exception is when technical requirements (separate platforms, regional teams with full autonomy) make subdomains necessary.
High DA vs. Low DA Site
現実世界の影響
ブランドがフランス向けに fr.site.com(サブドメイン)を立ち上げる
Starts with DA 1, takes 24 months to reach DA 30
Slow growth, limited competitive rankings
Brand launches site.com/fr (subdirectory) instead
Inherits DA 58 from main site immediately
Ranks competitively within 3 months, 6x faster traffic ramp