For the past year I have been running Net Uptime Monitor (netuptimemonitor.com) on Windows. I find it excellent. OK, it costs USD 10, but it really works. Every 10 seconds it pings Google, and if no response it will successively ping two other servers of your choice. If no response from any of the servers pinged it logs your internet connection as down, logging the time it went down and its duration. Over the past 24 hrs, for example, it logged my internet failing 84 times, the duration of the fails ranging from 10 secs to 1 hour !
Simple, to make sure you're getting what you pay for. This speed test is useful if you feel a connection slow down or want to see how your Internet is performing. This isn't like any other broadband speed test. TestMy's proprietary method is proven to help identify issues other speed tests fail to detect. The TMN Speed Test shows your true speed.