Is it down for everyone
or just me?

A website is down for everyone when independent synthetic network probes across multiple global Autonomous Systems (ASNs) fail to receive a valid HTTP 200 response or fail DNS resolution. If multi-probe monitors confirm global reachability while you cannot load the page, the failure is isolated to your local ISP routing, device DNS cache, active VPN, or browser cookies. You can isolate local issues by testing across an incognito window, clearing browser cache, and querying alternative public DNS resolvers such as 1.1.1.1 or 8.8.8.8.

Traditional down checkers rely on a single server probe, meaning any local network congestion, IP rate-limiting, or firewall rule encountered by that single node produces a false “Down” verdict. DownCheck eliminates single-point failures by executing two simultaneous check methods — a direct HTTP reachability probe and a 4-resolver DNS consensus across Google (8.8.8.8), Cloudflare (1.1.1.1), Quad9 (9.9.9.9), and OpenDNS. A verified outage is only declared when both methods confirm degraded or failed reachability.

An HTTP 502 Bad Gateway indicates that an edge proxy or CDN received an invalid response from the upstream origin server. An HTTP 503 Service Unavailable signifies that the target server is temporarily overloaded, undergoing maintenance, or unable to handle the request queue. An HTTP 504 Gateway Timeout occurs when the edge proxy waited for an upstream response but the connection timed out before the origin completed execution.

Discrepancies between mobile and desktop access are typically caused by differing network routes, separate DNS resolvers, or cached redirect loops. Mobile devices connected to cellular data use your carrier’s APN DNS infrastructure and dynamic IP pool, bypassing local Wi-Fi router DNS caches, local firewall rules, and browser extensions that may block desktop requests. Flushing your computer’s OS DNS cache (ipconfig /flushdns on Windows or dscacheutil -flushcache on macOS) resolves most device-level discrepancies.

A DNS failure prevents web browsers from resolving a human-readable domain name into its corresponding IPv4 (A record) or IPv6 (AAAA record) address, terminating the connection before an HTTP request can ever reach the origin server. DNS outages typically stem from authoritative nameserver DDoS attacks, misconfigured DNSSEC records, or registrar propagation delays during zone updates. DownCheck tests DNS health across four global resolvers (Google, Cloudflare, Quad9, and OpenDNS) to detect regional DNS poisoning and propagation blackouts.

DownCheck performs real-time synthetic probe checks on demand every time a query is executed, delivering millisecond-fresh connectivity telemetry. Additionally, our automated edge cron worker continuously monitors the top 55 global tech and enterprise platforms every 5 minutes, building a 24-hour historical uptime ledger stored on Cloudflare D1.