Rating subdomains

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.

The www subdomain

... the owner of the domain also controls the www subdomain. Since the www subdomain is commonly used as an alias for the main website hosted on the domain, we believe they should also share the reputation.

- Sami 27 May 2009

forum discussion: subdomain question - "www."

note:

If the subdomain contains "www" plus a string of integers such as: www1, www2, www123, www4321, WOT considers them to be equal to the parent domain as long as both of these conditions are true:

1. the host name matches the regular expression

   /^www(\d[^\.]*)?\..+\..+$/i

2. the parent domain is not a TLD (or an eTLD)

Multi-level subdomains

When a subdomain inherits the parent domain's reputation, the confidence level decreases to half on each hierarchy level. Depending on how reliable the parent domain's reputation is, at some point the confidence for the inherited reputation falls below the minimum threshold and the subdomain is shown as unrated. Here's an example, look at the confidence indicators:

http://www.google.com
http://www.1l.google.com
http://www.2.1l.google.com
http://www.3.2.1l.google.com
http://www.4.3.2.1l.google.com
http://www.5.4.3.2.1l.google.com
http://www.6.5.4.3.2.1l.google.com

So, currently the 6th level subdomains of google.com have no reputation in any rating component. If one of the parents lower in the hierarchy later receives ratings and gets a reputation of its own, the higher level subdomains will inherit its reputation instead.

— Sami

Flaws and possible improvements to algorithm

Suppose mybank.1.2.3.4.5.6.7.district.gov.cc is a phishing site. Further suppose WOT users give a low rating, including to every ancestor domain. mybank.1.2.3.4.5.6.8.district.gov.cc does not inherit the low rating at a significant level. A second issue is that an abusive subdomain created on a generally clean host is initially valued too highly and should not be affected by the reputation of the host qua host. So the neighbourhood of a novel subdomain could be estimated by looking first at children until significance is reached, then siblings, then the next level up and its siblings, then the next and its siblings, until a significant number of votes is reached. [Cedders]

For more reference, please read these blog posts:

• The Neighbourhood
• How many sites do we know?

  discusses how reputations traverse the domain hierarchy

see also: Shared domains