Downtime is any period when your website can't be reached or doesn't work properly for visitors.
Downtime is the time your website is unavailable. A visitor types your address and gets an error page, a blank screen or a connection that never finishes loading. It might last a few seconds during a server restart or several hours during a serious outage.
Downtime isn't always all or nothing. If your home page loads but the checkout throws an error, customers still can't buy anything, so for practical purposes that part of your site is down.
What causes downtime
The most common causes are:
- Server or network faults, such as failed hardware or a problem at the data centre.
- Resource limits on shared hosting, when a traffic spike uses up your entry processes or memory.
- Software errors, such as a broken plugin update or a PHP version your code doesn't support.
- DNS mistakes, such as wrong nameservers or a deleted A record.
- Expired domains or SSL certificates, which can make a site unreachable or show a security warning.
- Attacks, including floods of traffic and malware infections.
- Planned maintenance, which a good host schedules for quiet hours and announces in advance.
Why downtime matters for your website
Every minute offline can cost sales, enquiries and trust. Search engines also notice. A short blip won't hurt your rankings, but a site that is regularly unavailable when Google tries to crawl it can slip down the results. Email can be affected too if your mail runs on the same server.
Downtime vs uptime
Uptime is the flip side of downtime, usually shown as a percentage. The gap between figures that look similar is bigger than it seems:
- 99% uptime allows about 7 hours of downtime a month.
- 99.9% allows about 43 minutes a month.
- 99.99% allows about 4 minutes a month.
An SLA turns that percentage into a promise, usually backed by a credit if the host misses it. AblePage's plans carry a 99.9% uptime SLA.
How to reduce downtime
You can't control your host's hardware, but you can lower your own risk:
- Keep plugins, themes and your CMS updated, and test big changes on a staging site first.
- Turn on auto-renew for your domain so it never lapses.
- Use an uptime monitor that alerts you within a minute or two of an outage.
- Keep recent backups so you can roll back a bad change quickly.
- Put a CDN in front of busy sites to absorb traffic spikes.