I use Pingdom to report website uptime. Pingdom is configured to make an HTTP request to the host every minute, and report if it is unreachable. It'll also report an error if the host takes longer than 30 seconds to respond (Yes, that's not actually down, but if your site takes that long to respond it is unusable in my opinion). Pingdom performs this test from at least 3 servers worldwide, and reports a problem if 2/3 servers do no respond. This test is important if you are concerned about the reliability of your web host (this is important!) 
DreamHost performs pretty poorly in the Uptime Test, with an average result of 70.93 percent. It's best result was 100.000 % but it has been as bad as 0.000 %. DreamHost most recent result on Mar 16 was 0.000 %. Dreamhost has had a few significant outages, but I've seen worse. Their ping response time is pretty impressive, faster than most hosts, showing they have a decent network.
Site5 performs pretty poorly in the Uptime Test, with an average result of 88.81 percent. It's best result was 100.000 % but it has been as bad as 0.000 %. Site5 most recent result on Mar 16 was 0.000 %. Honestly, I expected Site5 to have better reliability. They've had a couple instances where my site was down for multiple hours, and that has ruined their overall average. But day-to-day they still have minor outages that annoy me.
InMotion Hosting performs miserably in the Uptime Test, with an average result of 98.86 percent. It's best result was 100.000 % but it has been as bad as 0.000 %. InMotion Hosting most recent result on Mar 16 was 100.000 %. When InMotion goes down, they typically are unavailable for only a minute or two. That's alright in my book. They're one of the only hosts that lets you know ahead of time of upcoming maintenance, and how long you can expect your server to be unreachable. I appreciate the communication.
Yahoo Small Business performs miserably in the Uptime Test, with an average result of 99.85 percent. It's best result was 100.000 % but it has been as bad as 82.778 %. Yahoo Small Business most recent result on Mar 16 was 100.000 %. Yahoo started out strong with their reliability, but tanked in November. Several outages lasting hours at a time - almost every day for two weeks straight. Unless they get their act together fast, I'd be careful with Yahoo.
MDDHosting performs under par in the Uptime Test, with an average result of 99.88 percent. It's best result was 100.000 % but it has been as bad as 64.583 %. MDDHosting most recent result on Mar 16 was 100.000 %. MDD has pretty average uptime reliability. Some hosts are more stable. Some are way worse. MDDHosting falls in the middle.MDDHosting does knock my socks off when it comes to their tech support. The longest I've ever had to wait for a response was 11 minutes. That's incredible. They must have a full staff working round the clock! Nice job, MDD.
Namecheap performs alright in the Uptime Test, with an average result of 99.93 percent. It's best result was 100.000 % but it has been as bad as 92.000 %. Namecheap most recent result on Mar 16 was 100.000 %. Namecheap has had a few significant outages (more than a few minutes) since I started testing them. It's nothing horrendous, but other hosts have better reliability.
StableHost performs mediocre in the Uptime Test, with an average result of 99.93 percent. It's best result was 100.000 % but it has been as bad as 73.000 %. StableHost most recent result on Mar 16 was 100.000 %. Stablehost really lives up to its name - proving itself with one of the best uptime percentages around, it truly is stable. Not sure I've witnessed an outage more than a minute or two with them. That's unheard of. Kudos, Stablehost.
Bluehost performs alright in the Uptime Test, with an average result of 99.94 percent. It's best result was 100.000 % but it has been as bad as 84.931 %. Bluehost most recent result on Mar 16 was 100.000 %. Bluehost had a terrible day back in August that's bringing their average uptime way down. Other than that they're usually pretty reliable.
GoDaddy performs great in the Uptime Test, with an average result of 99.96 percent. It's best result was 100.000 % but it has been as bad as 94.722 %. GoDaddy most recent result on Mar 16 was 100.000 %. GoDaddy has shown rocky uptimes when you first start hosting with them, however after a month things become pretty stable. Their tech team reached out to me to explain that they think it only happens when new customers get added to the server and apache needs to restart - and after the server is full it does not need to reload as often. The stats I've collected seem to support this theory, and they claim they're working on a solution.
HostGator performs above average in the Uptime Test, with an average result of 99.97 percent. It's best result was 100.000 % but it has been as bad as 97.000 %. HostGator most recent result on Mar 16 was 100.000 %. Back in 2013 HostGator had several outages that lasted days. While I wasn't recording detailed stats at the time, I can vouch that it was a miserable experience. Many blame the lack of reliability on their new data center, which they made everyone move to after they were bought out by EIG. To be honest, HostGator's downhill performance was the reason I created this site (I was too annoyed by them to let them get away with it).
Recent Raw Results from Mar 16
| Date | Uptime | Downtime | Outages | Avg Response Time |
|---|---|---|---|---|
| Bluehost | 98.000 % | 17 mins | 1 | 651 ms |