DNS_PROBE_STARTED

What’s actually happening

The page hangs and Chrome shows 'Diagnosing the problem' — it kicked off its own DNS probe because the normal lookup didn't come back. This is the in-progress/stalled state, distinct from DNS_PROBE_FINISHED_NXDOMAIN or _NO_INTERNET, which are completed failures. It often flickers and then resolves to a different DNS error once the probe finishes, or clears on retry. The hallmark is no response at all rather than a definite 'not found'.

Common causes

• The configured resolver (router, ISP DNS, or a manually set server) is down, overloaded, or not answering on UDP/TCP 53.
• A VPN or proxy that hijacks DNS dropped or froze, leaving queries pointed at an unreachable resolver.
• Local network just came up — Wi-Fi reconnect, sleep/wake — and the DNS path isn't ready yet, so the first lookups stall.
• A firewall or security suite is silently blocking outbound port 53.
• Stale or poisoned OS/browser DNS cache holding a half-open state.

How to fix it

1. Retry, then test a second siteReload once — a transient stall after a network change often clears itself. If other sites also stall on DNS but raw IPs work, it's your resolver, not the site. (`ping 1.1.1.1` succeeding while name lookups hang points squarely at DNS.)
2. Flush the DNS cachesBrowser: visit chrome://net-internals/#dns and click Clear host cache. OS: macOS `sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder`; Windows `ipconfig /flushdns`. This clears any half-open or stale entry the probe choked on.
3. Switch to a public resolverPoint the OS or router at 1.1.1.1 / 1.0.0.1 (Cloudflare) or 8.8.8.8 / 8.8.4.4 (Google). If lookups start working immediately, your previous resolver was the dead one. Test with `nslookup example.com 1.1.1.1` to confirm a known-good server answers.
4. Disable VPN/proxy and security DNS filteringTurn off any VPN, proxy, or 'secure DNS' feature in your AV temporarily. These reroute DNS and a frozen tunnel produces exactly this stall. If it works with them off, fix or reconnect that tool rather than leaving it disabled.
5. Restart the local network pathToggle Wi-Fi off/on, or reboot the router if every device stalls. A router whose own DNS forwarder has wedged will hang all clients until it's restarted — power-cycle it for 30 seconds.