In my quest to get some clear proof of the factors used to rank search result I'M this time taking a closer look at the importance of domain related info in googleland. Domain information such as DNS, age of domain and even the expiration date are used to distinguish between illegitimate and legitimate domains. Why are google doing this? Simply to get all the factors they can to get an internal "trust score". This "trust score" is used to eliminate "doorway" pages and spam in the search result. I'M not saying that it's working perfectly - but they are doing a pretty good job. Let's dig into more details in the patent. Key elements in the patent regarding domain information: Individuals who attempt to deceive (spam) search engines often use throwaway or "doorway" domains and attempt to obtain as much traffic as possible before being caught. Information regarding the legitimacy of the domains may be used when scoring the documents associated with these domains. Certain signals may be used to distinguish between illegitimate and legitimate domains. For example, domains can be renewed up to a period of 10 years. Valuable (legitimate) domains are often paid for several years in advance, while doorway (illegitimate) domains rarely are used for more than a year. The age, or other information, regarding a name server associated with a domain may be used to predict the legitimacy of the domain. A "good" name server may have a mix of different domains from different registrars and have a history of hosting those domains, while a "bad" name server might host mainly pornography or doorway domains. The newness of a name server might not automatically be a negative factor in determining the legitimacy of the associated domain, but in combination with other factors, such as ones described herein, it could be. DNS record for a domain may be monitored to predict whether a domain is legitimate. The DNS record contains details of who registered the domain, administrative and technical addresses, and the addresses of name servers For instance, whether physically correct address information exists over a period of time, whether contact information for the domain changes relatively often, whether there is a relatively high number of changes between different name servers and hosting companies.
DNS doesn't contain's all that information. It only contains information related domain name to IP address mapping. In other words, nameservers (NS), main exchangers (MX), host records, IP addresses, etc. Details of who registered the domain and administrative and technical addresses is contained in the WHOIS database.
IT's just one of many factors - I have been reading a lot of patent-docs from Google, which is public available.