Glossary · Monitoring

Probe Location

A probe location is the geographic point or network from which a monitoring service runs its checks, which shapes the latency and reachability it reports.

Updated October 14, 2026

A probe location is where a synthetic check originates: a data center or network in a specific city, country, or cloud region. Monitoring services run checks from one or many of these points to test your site as outsiders see it.

Why it matters

A site that is up in Frankfurt can be unreachable in Singapore because of a regional ISP issue, a broken CDN edge, or a routing problem. Checking from a single place gives a partial view and more false positives, since a local network glitch looks like an outage. Several probes let you tell a global outage from a regional one.

Example

Probe          Result        Time
New York       200 OK        180 ms
London         200 OK        230 ms
Singapore      timeout       10000 ms
Sydney         200 OK        410 ms

One failure out of four points to a regional problem, not total downtime. A common rule is to alert only when at least two probes agree, or when a failure is confirmed by a second location. Response times also differ by distance, so compare each location against its own baseline. You can test reachability from several places with the down-from-where tool.

Common mistakes

  • Alerting on the first failure from a lone probe.
  • Comparing timings across locations without considering geography.
  • Monitoring only from the region where your servers live, which misses CDN and DNS problems seen elsewhere.
  • Not allowlisting monitor IPs, so your firewall or bot protection blocks the checks.

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