A dangling record is a DNS entry, usually a CNAME, still pointing at a service you've cancelled, such as an old hosting app, storage bucket or landing page builder. If someone else creates a resource with that same name on that service, your subdomain starts showing their content. Delete DNS records for anything you no longer use.
What's the problem
A subdomain such as shop.yourdomain.com or old.yourdomain.com shows an error from a hosting service, a "no such app" page, or content you didn't put there.
Why it happens
- A service was cancelled but its DNS record was left in place.
- The record points at a name on a shared platform (cloud hosting, storage, site builders) that someone else can register once it's free.
How to fix it
- List every DNS record for your domain, especially CNAMEs on subdomains.
- For each one, check the service it points at is still yours and still running.
- Delete records for anything you no longer use.
- Make it a habit to remove the DNS record before cancelling a service, not after.
What Preventionlabs checks
One click runs the full report on your domain. For this problem it shows your DNS: nameservers, addresses, DNSSEC, and records pointing at services that no longer exist; your domain's registration and expiry date. With Cloudflare connected, it also shows DNS changes in the last 7 days.
Run your free reportYour first report is free, no card needed. Then A$50 a month, up to 10 domains. Read-only: it never changes anything.
Sources
- Microsoft: Prevent dangling DNS entries and avoid subdomain takeoverofficial docs
A subdomain takeover can occur when you have a DNS record that points to a deprovisioned Azure resource.