As explained on WOT's main Support page section: Rating Websites
- How does the system rate subdomains?
- Subdomains are often used with free hosting and social networking sites, for example. The WOT community can rate subdomains in exactly the same way as the members rate other domains. If WOT doesn’t have enough ratings for a specific subdomain, the subdomain inherits the parent domain's reputation. Once the system considers there to be enough supporting evidence to calculate a separate reputation for the subdomain, WOT will start to use it.
- Similarly, the reputation of each subdomain contributes to the parent domain's reputation. If a domain has lots of untrustworthy subdomains, its reputation will suffer, and, therefore, the reputation of any new subdomains will suffer as well. We designed this logic within the WOT system to model the way trust works in real life.
For more reference, please read these blog posts:
see also: Shared domains