The worst way to find out your website is down is from a customer, a day later. An uptime monitor tells you within minutes, and the percentages in hosting offers only make sense once you translate them into minutes.
In short
- Uptime is the percentage of time your website responds. 99.9% per month means the website can be unavailable for about 43 minutes a month.
- A promised percentage only counts if it's in the contract (SLA) and says what you get if it isn't met.
- Monitoring has to be done from outside the server, so it sees what a visitor sees.
- Good alerts come after a few failed checks, not the first one, so a one-second error doesn't wake you up.
The percentages, in minutes
The math is simple: a 30-day month has 43,200 minutes.
| Monthly uptime | Maximum downtime |
|---|---|
| 99% | about 7 hours and 12 minutes |
| 99,5% | about 3 hours and 36 minutes |
| 99,9% | about 43 minutes |
| 99,99% | about 4 minutes and 19 seconds |
Each extra “9” is ten times harder to reach and usually more expensive. For a business website, a few minutes a month change nothing; for an online store on a campaign day, they matter more.
SLA: commitment or marketing
A guaranteed availability level (SLA) is a clause in the contract: the provider promises a percentage and says what you get if it isn't met, usually a discount on the next invoice. A percentage shown on a website, with no clause in the terms, is just a description.
To be fair: NBT Host does not offer a contractual SLA on its hosting plans. What we do instead is give you the tools to see for yourself how your website is doing.
Why from outside the server
A website can go down for many reasons: the server, the network, DNS, an expired certificate, a code error after an update, a full database. A check run on the server itself doesn't see network or DNS problems. A proper monitor requests the page like a visitor would, from another server in another data center, and checks that the response is the right one.
How a good alert works
- The interval: a check every few minutes catches any outage that matters.
- Confirmation: the alert goes out after two failed checks in a row, not after one, so you don't get messages about a momentary error.
- Recovery: you also get a message when the website is back, so you know how long the outage lasted.
- The channel: email is good for the record; a phone notification is better for emergencies.
What an uptime monitor doesn't see
A monitor tells you whether the page responds. It doesn't tell you:
- whether the website is slow but still responding — for that you have the speed checks in our slow WordPress article;
- whether the cart or checkout stopped working, even though the home page opens;
- whether the form's emails stopped going out;
- whether someone has changed the content of the page.
For an online store, it's worth having someone place a test order after every update. That's what the Complete tier of WordPress Maintenance does, for example.
Monitoring at NBT Host
You can add Uptime monitoring to any hosting plan: the request comes every 5 minutes, from another data center, and you get an email when the website goes down, after two failed checks, and when it comes back. The history is in your NBT Account, and alerts can also reach your phone through the free ntfy app. On the Starter and Store plans it costs €1 per month or €11 per year.
WordPress Maintenance includes monitoring too: every 5 minutes on the Essential tier, every minute on Standard and Complete.
When you get an alert, the first step is to find out whether the problem is with the website or the server; what information to send us so we can fix it fast is in the guide How to ask for help.