The DNS hierarchy arranges these sections in a tree-like hierarchical structure: from the main domain to the subdomains:Top-Level Domain (TLD) : This is the main domain. On the other hand, doing SEO for subdomains correctly will help you:Target keywords and audiences that your main domain doesn’t cover. One more reason why copying your main domain’s backlink strategy may not help subdomains is that sometimes they differ dramatically. To make Google index your subdomains faster, ensure you interlink your main domain and subdomains. If you want to track subdomains together with the main domain, select the *.domain/* domain type when creating the project.