Microsoft has now confirmed that the cause of last week's Windows Update failure was a global outage at an unnamed external DNS service provider on January 29.
That outage left some Windows users in the US and UK unable to get security, software, and operating system updates from Microsoft's update service.
The issue affected Microsoft's update service for Windows users in the US on Comcast, as well as UK customers on BT Broadband. Some users were able to get updates working by changing their computer's DNS settings to Google's Public DNS.
Microsoft's explanation fills in some gaps about why users couldn't connect to Windows Update for several days after January 29.
Microsoft on late Monday said although the outage at an external DNS provider was fixed on the same day it occurred, "a few customers" continued to struggle to connect to Windows Update. The delay is because it takes a while for other downstream DNS servers to be updated with the corrected DNS entries for Windows Update.
"The Windows Update service was impacted by a data corruption issue in an external DNS service provider global outage on January 29, 2019," said Microsoft.
"The issue was resolved on the same day and Windows Update is now operating normally, but a few customers have continued to report issues connecting to the Windows Update service. We expect these issues will go away as downstream DNS servers are updated with the corrected Windows Update DNS entries."
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That would help explain why users on BT's forum continued reporting problems connecting to Windows Update over the weekend, while Comcast users reported the issue being resolved by Friday. Some customers at British ISP TalkTalk also reported problems connecting to Windows Update.
Microsoft is relying on Windows Update to resolve a long-running block on some Intel display drivers. That block was first imposed in November, shortly after Microsoft resumed the Windows 10 1809 update after suspending it due to a data-destroying bug.
The buggy drivers broke audio playback from monitors connected to a PC. Microsoft says Intel has now released updated drivers to PC OEMs, but these OEMs must make the new drivers available through Windows Update.
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