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Thanks Prashanth for the update. We were also able to work with a few other
folks from umbrella to understand the root cause.
Karthik
From: Prashanth Suvarna (psuvarna) <[email protected]>
Sent: Wednesday, December 31, 2025 10:48 AM
To: Stephane Bortzmeyer <[email protected]>; Karthikeyan Ravichandran
<[email protected]>
Cc: [email protected]
Subject: [EXTERNAL] Re: Re: Contacts from Cisco Umbrella / OpenDNS
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Hello,
We did have an incident yesterday where OpenDNS/Cisco Umbrella DNS resolvers
were not returning responses for certain domains (azure included) causing
client timeouts/retries.
Incident was resolved as of 13:50 UTC on 30th December. RCA work is currently
underway.
Status portal updates related to this incident is here
https://status.umbrella.cisco.com/incidents/49r2zg28sbny
Contains very little technical information unfortunately.
Thank you,
Prashanth
Cisco Umbrella/OpenDNS resolver team.
On 2025-12-30, 9:26 AM, "Stephane Bortzmeyer"
<[email protected]<mailto:[email protected]>> wrote:
On Tue, Dec 30, 2025 at 01:50:54PM +0000,
Karthikeyan Ravichandran via dns-operations
<[email protected]<mailto:[email protected]>> wrote
a message of 208 lines which said:
> From Azure/Microsoft, we are seeing customers of OpenDNS being unable to
> resolve domains hosted on Azure DNS. Are there any contacts of folks from
> OpenDNS that we can work with ?
It seems solved, no?
https://status.umbrella.cisco.com/
"
Monitoring - We identified issues and implemented a fix at 13:12 UTC.
Subsequent internal checks indicate everything is working fine now. The team
continues to monitor the situation closely.
Dec 30, 2025 - 13:26 UTC
Investigating - We are currently experiencing a service performance issue
affecting multiple data centers. You may notice an increased number of fail
opens and timeouts, resulting in delays or failures when making requests.
Our engineers are currently working to identify the root cause and implement a
resolution. Updates will be provided as new information becomes available.
Dec 30, 2025 - 12:14 UTC
"
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