Inbox, a Belgrade – based software company  , did some investigation into the online employment sector to compare the uptime of Serbia's well known job sites.

The survey focused on infostud.com and bestjobs.rs, the most popular job sites in the country. Both are general-purpose in that they serve a wide range of industries, without focusing on a specific one. To job seekers, their services are free of charge.

After two weeks of monitoring in January, Infostud, the #1 visited site, came out on top having showed the most reliability. The downtime of bestjobs.rs has been nearly two times that of Infostud.

Bestjobs.rs was unavailable for a total of 1 hour and 50 minutes. The site was completely inaccessible during that time. The first outage started on January 15 and lasted for 1 hour and 14 minutes. The second one followed on January 15 when the website was down for 36 minutes.

Infostud, on the other hand, was offline for 1 hour and 1 minute on January 18. It has had no additional downtime since.

Website	Downtime	Uptime
infostud.com	1h 1m	99.76%
bestjobs.rs	1h 50m	99.58%

On the other hand, careerbuilder.com, monster.com and indeed.com, the world's top three ranked sites in the job category, had zero downtime during the same period.

The survey was created using GIGRIB, an uptime monitoring service that lets you monitor up to 10 websites. It covers a large network of websites so you can always check how well a site included in the network is performing. GIGRIB is free of charge and is a part of advanced uptime monitoring service provided by Pingdom , the fastest-growing uptime monitoring service in the world.

Uptime in numbers

Uptime is the time your website is accessible on the Internet. Good uptime means your site is available to visitors whenever they visit your website. It's a synonym for reliability.

The reasons behind downtime are various from poorly written software, human error, system upgrades to power outages, but human error is the biggest contributor and is said to account for 50-80% of network device outages.

Whether your site will have good uptime or not greatly depends on your hosting provider. Most hosters claim to offer a 99.9% uptime guarantee, which means you will have no more than 43 minutes of total downtime a month or 8 hour and 45 minutes a year. The table below shows uptime calculated as a number of minutes, hours and days of outage.

Availability	Daily	Monthly	Yearly
99.999%	00:00:00.4	00:00:26	00:05:15
99.99%	00:00:08	00:04:22	00:52:35
99.9%	00:01:26	00:43:49	08:45:56
99%	00:14:23	07:18:17	87:39:29

To be 99.999% available or achieve 'five nines' uptime is ideal and means your site should not be down more than 5 minutes a year, excluding planned downtime. This is hard and fairly expensive to achieve and most services on the Internet you cannot expect to be available for five nines. According to the Uptime Institute, only 10% of sites are 99.999% available.

Downtime is inevitable. Not even the busiest sites on the planet are immune to it and frequently have trouble being available around the clock. In 2008, Amazon was down for 4 hours and 38 minutes, which, by some estimates, cost the company over a million dollars an hour in sales.

Facebook, a groundbreaking online community and the most visited social networking site in Serbia, was down for a total of 2 hours and 29 minutes in the first quarter of 2008. MySpace was unavailable for 1 hour and 5 minutes while Twitter was offline for a total of 37 hours and 16 minutes. The full list is available on the Pingdom blog.

In 1995 when Netcraft did its first survey there were 18,957 sites on the Internet while in January 2009 the number rose to 185,497,213 million sites. Keeping them all up all the time seems like a mission impossible.