This Cloudflare security tool actively blocks and displays an error when a DNS hostname is configured as a CNAME record that points across different user accounts. It is designed for Cloudflare administrators and users to prevent unauthorized linking of domains and enforce account isolation for security and integrity.

• Cross-Account CNAME Blocking: Automatically detects and prevents a DNS CNAME record from resolving if it is configured to point from one Cloudflare user account to a resource in another account.
• Security Policy Enforcement: Enforces Cloudflare's internal security rules that prohibit sharing CNAME records between accounts, mitigating risks from misconfiguration or malicious linking.
• Clear Error Messaging: Provides a specific error page (1014) with a detailed explanation when this condition is encountered, informing users of the exact policy violation.
• Guidance for Resolution: The error interface includes references to relevant documentation, such as guidance for correctly configuring custom domains for services like R2, to help users resolve the underlying configuration issue.