Flush DNS cache and compare resolvers

When to use this guide

Use this when Chrome reports DNS failures, a domain works for some people but not others, or a recent DNS change seems invisible from one device or network.

Steps

1. Check the exact hostname. Test the full hostname, including subdomain. example.com and www.example.com can have different DNS records.
2. Compare public resolvers. Query at least two resolvers such as your ISP resolver, 1.1.1.1, 8.8.8.8, or a provider diagnostic tool.
3. Check authoritative answers. If public resolvers disagree, query the authoritative nameservers or use a DNS checker to see whether the records are published correctly.
4. Flush local DNS cache. Clear the operating system DNS cache and then restart or refresh the browser DNS cache if needed.
5. Try another network. A mobile hotspot helps separate local router or ISP resolver issues from site-wide DNS problems.
6. Wait for TTL when appropriate. If old records are cached and the authoritative records are correct, avoid repeated changes. Let the previous TTL expire.

Verify

The hostname should resolve to the expected record from multiple resolvers, and the browser should move past DNS resolution to an HTTP response.

Rollback or escalate

If authoritative records are wrong, fix them at the DNS host or restore the previous known-good record. Escalate with the hostname, expected record, actual answers, resolver used, and TTL.