Microsoft's cloud systems are up-and-running again today after Hotmail, Office 365 and Skydrive all experienced an outage in the early hours of the morning.

This is the second outage that Microsoft has experienced since Office 365 launched in June of this year. As with the first time, a Domain Name System (DNS) error is thought to be the cause of the problem, with the Hotmail email system and Skydrive document sharing systems affected this time around.

On Twitter, Microsoft said: “Preliminary root cause suggests a DNS issue, though we're still working hard to restore.”

The outage impacted users across the globe and took place between 4am and 6.30am GMT. Though outside of business hours for Europe and North America, users in Asia will have felt the disruption to their working day.

In an update on its live blog, Microsoft said: “We are working on propagating the DNS configuration changes and so it will take some time to restore service to everyone. Again we appreciate your patience.”

The US computer giant has tried to assure its users with an SLA agreement which offers refunds when its uptime fails. After the last failure, Microsoft gave customers a 25 per cent credit note on future invoices.

These two outages of Microsoft's Office 365 cloud-based services within the space of a month and so soon after its launch will have done the system no favours in its battle against Google Apps. As these two suppliers go head-to-head to try establish themselves as the dominant force in the cloud computing world, uptime guarantees are vital.

Users demand assurances that they will be able to access their files, informations and data around the clock and around the world. Microsoft's ability to meet such demands will now be under scrutiny following this second major outage.

Are you an Office365 user? Were you affected? Email your thoughts to dom.pollard@thecloudcircle.com.