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What Does 99.99% Uptime Really Mean?

Author , Posted In Posted in: IT Consulting

Ever have to fight with your Internet Service Provider about downtime and getting credited because the internet was down for a lengthy amount of time? Does your web hosting company promise a high percentage of “uptime”? With the recent GoDaddy DNS outage, a lot of people are asking what exactly the 99.99% update guarantee means.

It may not seem like a lot, but what is the difference between 99.9%, 99.99%, and 99.999%? That one extra “9” can make a lot of difference in the ability to uphold an SLA. Below is a chart that is based off of a one year period comparing the different percentages.

Uptime Guarantee    |    Minutes    |     Hours    |    Days

           99%                        5256           87.6          3.65

           99.9%                     525.6          8.76         0.365

           99.99%                   52.56         0.876       0.0365

           99.999%                 5.256        0.0876     0.00365


With that little tid-bit of information, let’s talk about SLA’s and what exactly these mean. According to Wikipedia, an SLA is the entire agreement that specifies what service is to be provided, how it is supported, times, locations, costs, performance, and responsibilities of the parties involved.

As an example, GoDaddy guarantees “Fast Performance, 99.999% uptime guarantee.” Comparing that number to the chart above, their acceptable downtime would be 5.256 hours if that was on a year term. But are they basing this number off of a year, 2 years, since their last downtime, or since they were founded? That number can fluctuate in a HUGE way if that number was 10 years compared to 1 year. This is where the terms of the contract come in. Ironically enough, GoDaddy has removed their 99.99% uptime guarantee claim since the major outage that occurred this week.

Companies often have hours set aside for planned downtime or maintenance. Some service providers do not qualify “maintenance” time as down time and so with this, they are able to keep an all-around SLA and this prevents them from having to credit accounts for breaking their agreement.

The point to all of this is that there is a lot of “fine print” when it comes to contractual SLA’s. I recommend that you review every aspect of your contracts and go through them with a fine toothed comb.