Finding Subdomains: The Best Tools

HOW TO FIND SUBDOMAINS

Hidden or forgotten subdomains can often impede the progress of a digital marketing campaign if they muddy the waters or create duplicate content issues.

WHY IS IT IMPORTANT TO FIND SUBDOMAINS?

With Google rolling out ever more aggressive algorithms to detect either offsite gaming of SEO or poor or duplicated content onsite, it is ever more imperative to identify where thin or duplicated content may exist – often hidden within forgotten subdomains or staging sites.

A significant problem, however, is that finding areas of duplicate content is not fool proof – other than cutting and pasting content and spot checking search results there are no effective ways to find duplicate content.

When it comes to subdomains, a very common problem we find is that in-house digital marketing teams and developers change over the years. In many cases, the history or knowledge of subdomains is lost, and sometimes, it can be impossible to find a comprehensive list of forgotten subdomains when starting an SEO campaign with a new client.

SUBDOMAINS CHECKERS

Rather than rely on what can at times be sketchy subdomain knowledge, at WMG we use several online tools that are readily or freely available as well as subdomain checkers which are subscription based.

Listed below are our favourite tools that will show you how to find subdomains.

1.- Pentest Tools (Free up to 20 daily credits)

A great and in-depth crawl of a domain and very simple way to find subdomains. Results also have the added benefit of having IP addresses and can easily be added to working documents for further analysis and decision making.

2.- DNS Dumpster (free)

Another great subdomain finder with the added benefits of a clean XLS output. Open the XLS output and use other tools such as SEO Tools for Excel or Screaming Frog to find the response codes and then you can manually check them.

DNS Dumpster also provides a great visual of hosting locations and IP blocks which make later decision making easier.

3.- Netcraft (free)

A much quicker – but arguably less in-depth – subdomain checker that works on the principle of looking up sites that contain a word within the domain. Unfortunately no clean output but a quick and easy check for smaller websites.

The tools listed above can be used individually – depending on the scale of the domain or client – or collaboratively. More often than not, we would suggest using all three and collating findings into one master document which can be used to rationalize hidden subdomains.

By David Shave, Senior Technical Account Manager