Domain-name monitoring is a well-established component of a holistic brand protection programme. This reflects the central role played by domain names as an element of the IP of any business with an online presence, and the potential for third-party domain names to be utilised as part of abuse or infringement campaigns. A related issue is the use of brand references in the subdomain part of a URL – where the subdomain is the part before the domain name, such as ‘play’ in play.google.com – which can similarly be used in cases of false affiliation, brand impersonation and traffic misdirection. However, subdomains present an entirely different prospect from a discovery point of view, since there is no mechanism (akin to the process of zone-file analysis which allows for detection of domain names themselves) to comprehensively detect brand-related subdomains.  

In an article for Circle ID, David Barnett explores the effectiveness of a range of approaches to identify relevant subdomains. The techniques include the use of search engines to identify indexed content, queries to a range of public databases, and ‘brute-force’ searches. As a case study, we consider the discovery of subdomains of each of the top 50 most popular global websites. 

Using the full set of discovery methods, over 640,000 unique subdomains of these 50 domains were identified, including instances up to 231 characters in length, with 28 subdomain levels. A detailed analysis was then carried out in order to identify the most frequently occurring keyword patterns, and tie them to popular use-cases. The next stage of analysis considered the presence of potentially abusive subdomains, using the Apple brand as an example, with numerous cases of live potential infringements identified.  

Overall, the study highlights the popularity of subdomain usage, and the significant potential for associated abuse, illustrating the importance of discovery tools able to detect relevant subdomains. This is an area where traditional monitoring methods tend to provide relatively poor coverage. The analysis has shown that the application of a range of discovery techniques working together can achieve a relatively good level of detection. Accordingly, best practice for the most sophisticated brand monitoring solutions going forward would be the inclusion of these relevant data sources.