14 DAY TRIAL // On September 8th, 2011, a few Windows Live services, including Hotmail and SkyDrive suffered an outage caused by a Domain Name Service (DNS) issue, according to Arthur de Haan, vice president, Windows Live Test and Service Engineering.
Microsoft became aware of the problem at approximately 8:00 PM PDT and started working on a fix immediately. Hours later the same day, at 10:23 PM PDT the services had begun being restored.
The software giant stressed that Windows Live users did not lose any of their data, or had any compromised, for that matter.
“So, what happened? A tool that helps balance network traffic was being updated and the update did not work correctly. As a result, configuration settings were corrupted, which caused a service disruption,” de Haan added.
Microsoft had already dealt with the source of the Windows Live downtime ahead of 11:35 PM PDT, but customers needed to exercise their patience a tad longer for full functionality of Hotmail and SkyDrive to be restored. Such updates roll out gradually worldwide and don’t reach all users simultaneously.
The corrupted file in Microsoft’s DNS service was caused by a couple of concurrent rare conditions, the Redmond company explained.
“The first condition is related to how the load balancing devices in the DNS service respond to a malformed input string (i.e., the software was unable to parse an incorrectly constructed line in the configuration file),” de Haan explained.
“The second condition was related to how the configuration is synchronized across the DNS service to ensure all client requests return the same response regardless of the connection location of the client. Each of these conditions was tracked to the networking device firmware used in the Microsoft DNS service.”
The promise from Microsoft is that a variety of measures have been taken, and additional work will be done to ensure that the issue which caused the Windows Live outage on September 9 will not be repeated.