Unbound DNS checker

Use this server to make DNS queries against an Unbound instance and get logs. The Unbound instance is configured very similarly to Let's Encrypt's production servers, and is started fresh for each query so there are no caching effects. If you are having trouble diagnosing a DNS problem reported by Let's Encrypt, this may help you debug it. Common problems include: invalid DNSSEC records, failure to implement DNS 0x20 (mixed case), timeouts, and flaky servers.

Once you've made a query, you'll get a URL you can share. Note that URLs are currently only persisted in memory, so they are likely to disappear after a few hours or days when the server is restarted. Source code on GitHub. View the Unbound config.