How to Fix: dnsmasq circular loop error

The 'dnsmasq circular loop error' occurs when two routers, A and B, are configured to use dnsmasq for DNS resolution. In this scenario, router A is upstream of router B and both have their own domain configurations. The issue arises when a query from router B cannot find the requested record in its local cache and sends a request to router A, which also fails to find the record but uses the 'server' directive to forward the query back to router B. This creates an infinite loop of queries between the two routers.

This circular loop can be frustrating for network administrators as it causes unnecessary traffic and delays in resolving DNS queries. In this troubleshooting guide, we will walk through the steps to identify and resolve the issue.

🛑 Root Causes of the Error

• The primary cause of the 'dnsmasq circular loop error' is due to the incorrect configuration of the 'server' directive in dnsmasq.conf. When a query cannot find the requested record, it sends a request to the upstream router with the 'server' directive set, which can lead to an infinite loop if the upstream router also has the same directive configured for the same domain.
• Another possible cause is the lack of a 'hide-stdin' directive in one or both routers. If this directive is missing, dnsmasq will continue to use the original IP address of the interface as the server IP, leading to an infinite loop.

🚀 How to Resolve This Issue

💡 Conclusion

To resolve the 'dnsmasq circular loop error', it is essential to identify and correct the configuration issue. By disabling the 'server' directive or configuring the 'hide-stdin' directive, network administrators can prevent the infinite loop of queries between routers A and B. Regularly checking the dnsmasq logs for any errors or warnings will help ensure that the fix has been successful.