Referenced domain does not resolve

What it detects

A domain referenced in the site's machine-readable agent instructions does not resolve in DNS.

Why it matters

Agents follow documented links automatically, with no human to notice a dead host; an unregistered domain named in published instructions is a slot someone else can take over.

How to fix

Update or remove the dead domain references in your agent-facing docs. Agents follow documented links automatically, with no human to notice the host is gone. If a domain you used to own appears here, re-register it or purge every mention — an expired domain named in live instructions is a takeover slot.

Example

https://docs.acme-corp.io/agents # NXDOMAIN

References

• llms.txt specification
• RFC 2606 — Reserved Top Level DNS Names
• RFC 9421 — HTTP Message Signatures
• Cloudflare verified bots