Reading an uptime promise
Percentages near 100 are deceptive. The difference between 99% and 99.9% sounds trivial but is the difference between more than three days of downtime a year and under nine hours. Each extra nine is roughly ten times harder to deliver, and the price tends to reflect it.
What is usually excluded
- Planned maintenance windows.
- Problems caused by your own software or configuration.
- Attacks and events beyond the provider's control.
- Short outages under a certain length, in some contracts.
What you get when they miss
Normally a credit against future fees, often a small percentage of the monthly cost, and often only if you file a claim within a few days. It rarely covers lost sales. If your business depends on uptime, your real protection is architecture: a second server, a CDN that can serve cached pages when the origin is down, and monitoring that tells you before your customers do.
Monitoring it yourself
Free external monitors check your site every minute or so from several places and email you when it fails. They also give you your own record of uptime, which is useful if you ever need to dispute a figure.