Every site that gets added to Oh Dear will automatically have its uptime monitored.
Each site is monitored from a primary location and verified from a secondary location. You can choose your primary location from within the Oh Dear dashboard.
If the primary location reports an error to Oh Dear, the secondary location is used to verify the problem. We'll only trigger an alert if both the primary and the secondary checks report the site as down.
This prevents any false alerts.
Uptime check options
To check the uptime, we'll send a simple
GET request to the site you provide. If it responds with a
2xx HTTP response, the check passes. In the settings screen of the site, there are several options available to customize this check:
- look for string: we can check if a given string is found on the result. If it is not found, we'll mark the check as failed. This is sometimes called a "check string" or "HTML verification".
http verb: instead of a
GETrequest, you can specify that the check should be performed with a
payload: when not using a
GETrequest to check your site, you can specify a payload. This payload will be sent along as the form parameters when checking your site.
- headers: you can specify up to 10 extra HTTP headers that should be used in the uptime check request.
Uptime checks happen every minute from the primary location.
As soon as the primary location detects a problem, the secondary location will be used to verify it.
If you were to put this on a timeline, it would look like this.
|15:22h||PROBLEM||+ Secondary location|
|15:23h||PROBLEM||+ Secondary location|
|15:24h||PROBLEM||+ Secondary location|
|15:24h||Notification fired: site DOWN|
|15:25h||PROBLEM||+ Secondary location|
|15:26h||Notification fired: site UP|
The first problem is detected at 15:22h and the second location is immediately used to confirm the problem.
If both locations confirm the site is down for 2 minutes in a row, you will be notified of this event.
The check at 15:26h confirmed the site was back online, so you'll be notified of that too.
Note: you can overwrite the behaviour for when we alert you, by changing the website settings in your dashboard.
What is downtime?
We classify downtime in 2 ways:
- If we receive anything other than an
HTTP/2xxresponse code on the check page, we consider it down. Note that we will follow
HTTP/302redirects. The final result of the redirect should be an
- If we receive a
HTTP/2xxresponse, but we didn't find the optional check string specified on the site settings screen, we consider it down.
- If the site takes more than 5 seconds to load, we consider it down.
Any of those events marks the site as unavailable.
For example, an
HTTP/204 No Content response will also be considered "online".
If the site took too long to load, we can only show you that it timed out.
Operation timed out after 5000 milliseconds with 0 bytes received
However, if the site responded with a status code other than
HTTP/200, we will show you the exact HTTP response headers we received to help you troubleshoot, along with the IP(s) we used to monitor your site.
Downtime is verified from multiple locations, those locations and their IP addresses are confirmed in the notification:
Monitored from: Paris, France (188.8.131.52, 2001:19f0:6801:5f3:5400:1ff:fe38:3572) Verified downtime via: Chicago, USA (184.108.40.206, 2001:19f0:5c01:7c0:5400:1ff:fe38:72f1)
All debug-headers are supplied for you, together with copy/paste cURL commands for you to replicate our exact check.
With that information, you should have all the needed information to troubleshoot the problem.
Each month, you'll receive an uptime report for all your sites to show you how well they performed.
In it, we show you what percentage of uptime each site received, as monitored via its primary location. If a site is down, it'll be subtracted from the total uptime.
Here's what that might look like.
Want to know what happened during that month? Click through each site and navigate to the uptime page in the Oh Dear dashboard to see the timings of each downtime.