Feeds

Revealed: How Microsoft DNS went titsup globally on Xbox One launch day

A 'Group Policy Object' snafu brought Redmond to its knees

Beginner's guide to SSL certificates

Exclusive Microsoft's major outage last week was caused by a policy rollout that derailed its own DNS servers – a blunder that also downed some of the tech giant's internal services.

The outage hit on Thursday, during which key websites such as Xbox.com and Outlook.com were knocked over, connectivity to the Office 365 online software suite axed, and multiple Azure cloud services were cut off from the outside world.

We've also heard from multiple sources that the blunder scuppered parts of Microsoft's on-campus networks as well, rendering systems inaccessible to employees.

For a company that prides itself on becoming a "services and devices" firm, having multiple online services fall offline at once is very bad. XBox.com, for instance, was taken down just Microsoft's Xbox One console went on sale worldwide.

Now El Reg can reveal that the root cause of this mega-fail was a flubbed change to an Active Directory Group Policy, which ultimately rendered the company's DNS servers inaccessible.

The mistake "inadvertently blocked incoming DNS queries to Microsoft DNS servers," Microsoft wrote in a "post-incident review" document, seen by The Reg and distributed to affected customers. "All zones owned by Microsoft authoritative DNS infrastructure may not have resolved depending on client-side TTL."

In the report, the company said the outage started at about 10.10pm UTC on Thursday, when "network engineers observed difficulty making changes to DNS records on the authoritative DNS infrastructure". The system was back on track by 11.30pm.

At first, we're told, engineers tried to revert the Group Policy Object change, and started a forced refresh of group policy across DNS server infrastructure. No improvement was observed, and so at 11pm UTC they rebalanced their DNS server infrastructure. This helped, and at 11.15pm they executed a script to reboot the balancing of DNS servers. As this propagated, things got better.

Nonetheless, 80 minutes is not a brilliant amount of time to lock out folks from critical business services. During the outage, users may have had difficulty trying to access crucial online Microsoft services such as Exchange, SharePoint, Lync, and others due to "name resolution issues".

The impact on users also varied according to their own DNS time-to-live (TTL) settings, the company said. To fix the problems Microsoft plans to "improve policy change procedures", it said.

It will also "update communication tools to improve resiliency" as it was unable to post to its services' health dashboard during the incident because "the DNS issue impacted internal service".

DNS is a tricky tech to manage when you're a global company fielding a vast quantity of online systems, but it strikes us that Microsoft made DNS changes a single point of failure – and this needs to be dealt with.

We're also confused as to why Microsoft neglects to publish reports like this in the open, instead treating them like valuable corporate information (they aren't) and sending them only to affected customers. If you receive other ones, don't hesitate to get in touch. ®

Providing a secure and efficient Helpdesk

More from The Register

next story
Doctor Who's Flatline: Cool monsters, yes, but utterly limp subplots
We know what the Doctor does, stop going on about it already
Facebook, Apple: LADIES! Why not FREEZE your EGGS? It's on the company!
No biological clockwatching when you work in Silicon Valley
'Cowardly, venomous trolls' threatened with TWO-YEAR sentences for menacing posts
UK government: 'Taking a stand against a baying cyber-mob'
Happiness economics is bollocks. Oh, UK.gov just adopted it? Er ...
Opportunity doesn't knock; it costs us instead
Ex-US Navy fighter pilot MIT prof: Drones beat humans - I should know
'Missy' Cummings on UAVs, smartcars and dying from boredom
Sysadmin with EBOLA? Gartner's issued advice to debug your biz
Start hoarding cleaning supplies, analyst firm says, and assume your team will scatter
Zippy one-liners, broken promises: Doctor Who on the Orient Express
Series finally hits stride, but Clara's U-turn is baffling
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Win a year’s supply of chocolate
There is no techie angle to this competition so we're not going to pretend there is, but everyone loves chocolate so who cares.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.