When you have control over multiple sub domains or even top level domains, this is referred to an ‘administrative relationship’. When Google becomes aware of administrative it can have both positive and negative consequences, including the following:
- Distribute authority – if Google knows you control other authoritative sites, it will possibly want to recognise this authority when you launch new sites. e.g. if eBay were to launch a site in Ecuador, Google would want to transfer some of the authority it has built up through its US site.
- Subdomains – often businesses launch blogs etc. on subdomains as it may be easier from an administrative or development perspective. Google then decides whether the subdomain will be given the same authority of the main site or not. Making the subdomain’s association with the main site obvious to Google, can help in the administrative relationship being recognised.
- When you have multiple versions of your site in various languages Google will use the administrative relationship to transfer the authority onto the different versions of the site.
- Identity – Google is working to figure out identities across the web.
- Diminished link equity – because Google understands that when one person has administrative authority over a number of sites, they are able to control all of these links, Google gives less weighting to links between domains with the same webmaster. This is why blackhat SEOs try and hide their ownership of multiple sites to Google.
- Link Schemes/Bad Neighbourhoods – Even when blackhats do hide their administrative authority between domains, if Google sees a significant number of sites all linking between each other, this can indicate something manipulative and attract a penalty.
- Penalties – Sometimes when a webmaster gets a penalty on their domain, they get fed up and totally move the site to a new domain without a penalty and any backlinks. As Google becomes more sophisticated, it is able to see these site moves and sometimes transfers the penalty to the new domain.
How does Google detect these Administrative relationships? Well, no one really knows, but it is generally agreed amongst SEOs that Google looks at the following:
- WhoIs records – freely available information on the web of who has registered a domain.
- Hosting/IP address – Spyonweb.com will show one domains relationship with any others.
- C-block (changing with introduction of IPv6) – traditionally Google looked at links from IPs with the same c-block to give clue about site ownership.
- Analytics Code on multiple domains
- Advertising code on multiple domains
- Link patterns – Google has the biggest graph of links the world knows and this can make associations on the web pretty obvious.
While the traditional signals are commonly known and many public, content signals are also starting to be taken to account by Google to determine site ownership. This includes:
- Identical or similar content, formatting, images, CSS and details on contact pages across multiple domains.
- Page level signals – authorship across multiple domains and the Hreflang tag if trying to establish ownership for foreign language sites.