Can someone take over my old subdomain?

Short answer: yes, if a DNS record still points at a service you've stopped using, like an old app, store or hosting account. Someone else can sign up for the same address on that service, and your subdomain then shows their content.

How to check it yourself

List your DNS records at your DNS provider.
For every CNAME, open the address it points to and check you still own and use that service.
Delete records for anything you no longer use.
If a subdomain shows content you didn't put there, delete its record straight away.

Why it matters

A taken-over subdomain sits on your real domain, so whatever is put there looks like it's yours: phishing pages, malware or spam. Browsers and visitors trust it because the address is genuine, and it can be used to read cookies set for your main domain.

Common causes

A CNAME still points at a hosting, app or store account that was closed.
A cloud storage bucket or app was deleted but its DNS record wasn't.
A trial or demo setup was abandoned with its record still live.
A project moved providers and the old record was never cleaned up.

What Preventionlabs shows

Every report checks your domain and its www address for records that point at something that no longer exists, and says which one and where it points, for example "www.example.com points to old-app.example-host.com, which no longer exists", with the fix: delete the record, or re-create what it points to.

Other subdomains you've created need the manual steps above.

Price

First report free, no card needed. Then A$50 a month, up to 10 domains.

Run your first report free