Knowledge

DNS_ERROR_CNAME_LOOP - 9707 (0x25EB)

CNAME loop detected.

Updated: Feb 21, 2026

Technical Background

The DNS_ERROR_CNAME_LOOP error code, with the numeric value of 9707 and the hexadecimal representation of 0x25EB, indicates a specific condition in Domain Name System (DNS) resolution where a circular reference is detected. This typically occurs when a DNS query results in an infinite loop due to multiple CNAME records pointing back to each other.

Error Details

The DNS_ERROR_CNAME_LOOP error signifies that the DNS resolver encountered a situation where a CNAME record points back to another CNAME record, creating a loop. This can lead to recursive queries that never terminate, potentially causing performance degradation or even system instability in network environments.

Common Causes

  • Invalid Parameter Values: Incorrectly configured CNAME records leading to circular references.
  • Incorrect Object Type: Misconfiguration of DNS records where a CNAME record incorrectly points to another CNAME instead of an A (IPv4) or AAAA (IPv6) record.
  • Exceeding Limits: In rare cases, the resolver might hit internal limits on recursive queries.

Real-World Context

This error can occur in various network configurations where DNS records are improperly set up. For example, if a domain name is configured with CNAME records that point to each other, it will result in this error being reported by the DNS resolver.

Is This Error Critical?

The DNS_ERROR_CNAME_LOOP error is critical because it can lead to recursive queries that never terminate, causing performance issues and potential network instability. It is essential to address such errors promptly to maintain a stable and efficient network environment.

How to Diagnose

To diagnose this issue, follow these steps:

  1. Review Operation Context: Check the DNS configuration for any circular references.
  2. Validate Parameters: Ensure that all CNAME records are correctly configured and point to valid A or AAAA records.
  3. Confirm Object Types: Verify that no CNAME record points to another CNAME, as this will cause a loop.

How to Resolve

To resolve the DNS_ERROR_CNAME_LOOP error, take these actions:

  1. Correct Parameter Usage: Ensure all DNS records are correctly configured.
  2. Adjust Operation Context: Modify any incorrectly configured CNAME records to point directly to valid A or AAAA records.
  3. Restore Data: If necessary, restore the correct configuration from a backup.

Developer Notes

Developers should ensure that their DNS configurations do not contain circular references. This can be achieved by carefully designing and testing DNS records before deployment.

Related Errors

  • DNS_ERROR_NAME_NOT_RESOLVED (9013): Occurs when the domain name cannot be resolved.
  • DNS_ERROR_NO_SUCH_HOST (9012): Indicates that the host does not exist in the DNS system.

FAQ

Q: What causes a CNAME loop?

A: A CNAME loop occurs when multiple CNAME records point to each other, creating an infinite recursive query cycle.

Q: How can I prevent this error from occurring?

A: Ensure that all CNAME records are correctly configured and do not form circular references. Regularly review DNS configurations for accuracy.

Summary

The DNS_ERROR_CNAME_LOOP error is a specific condition in DNS resolution where multiple CNAME records create an infinite loop, leading to recursive queries that never terminate. This can cause performance issues and network instability. Proper configuration of DNS records and regular maintenance are essential to prevent such errors.