# Monitor types

> InfraNest can watch ten different kinds of target. Pick the one that matches what you want to check.

Source: https://infranest.io/docs/check-types
Last updated: 2026-09-19

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Monitors are how InfraNest keeps an eye on your servers, sites, and services — this article explains the different kinds of checks you can run and how to make sense of SSL warnings.

## Overview

- InfraNest supports ten monitor types, each suited to a different kind of check.
- Pick the type that matches what you actually want to watch, rather than defaulting to one type for everything.
- Some types do more than just check status — for example, an SSL monitor also adds the certificate to your certificate list.

## Choose the right monitor type

1. **HTTP** — confirms a website or URL is reachable and healthy, and can detect slow responses.
2. **API** — checks that a JSON or multi-step API endpoint behaves as expected.
3. **Port (TCP)** — checks that a TCP port is open and accepting connections.
4. **SSL** — checks that a certificate is valid and not near expiry, and adds it to your certificate list.
5. **DNS** — checks that a DNS record resolves, optionally matching an expected value.
6. **Keyword** — checks that a page contains (or doesn't contain) some expected text.
7. **Redirect** — checks that a URL redirects to the address you expect.
8. **Ping (ICMP)** — checks that a host answers a ping.
9. **Heartbeat** — a "dead man's switch" for cron jobs; your job must check in each interval or you're alerted.
10. **Third-party** — mirrors another company's public status page, so their outages show up on yours.

> [!TIP]
> For an HTTP check you can also turn on an **SSL sub-check** to watch the certificate's expiry, without creating a separate SSL monitor.

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## Understand SSL monitor warnings

1. Open your SSL monitor and find the **Warn when expiring within (days)** setting — this is how many days before expiry you want to be warned, with 30 as a sensible default.
2. Know that a certificate expiring soon does **not** turn the monitor red. The certificate still works, so the monitor stays up and no incident opens — you're just notified by email or your chosen destination, with details on the monitor's detail page. Only an actually expired certificate counts as an outage. This matters if the monitor is a component on a public status page, since an upcoming renewal isn't something your customers need to see as a problem.
3. Note that self-renewing certificates are judged differently. Most certificates today (for example, from Let's Encrypt or similar services) are issued for 90 days and renew automatically with 30 days remaining — so a healthy certificate would otherwise trigger a warning on every renewal.
4. For these, InfraNest watches the *renewal* instead of the expiry date, and alerts you only if the renewal should have happened and didn't — leaving you around 25 days to fix it.
5. Check whether a certificate is treated this way on the monitor's detail page, under **Renewal**.
6. If it's set up incorrectly, correct it on the certificate itself in your certificate list.

## Tips

> [!NOTE]
> Only an expired certificate is treated as an outage — an expiry warning is informational and won't affect your public status page.