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A change was implemented to fix the automatic renewal of the OV certificates, which triggered the HA Proxy service to restart. However, a missing DNS record for dndrdc01.win.dante.org.uk caused the restart of the HA Proxy service service to fail.
The server dndrdc01 was decommissioned on 22 May 2020, but the record was cleaned up recently. We still don't know the exact time when this record was expunged, however, a similar issue was observed on another VM this morning. This needs to be investigated further with the help of IT.
A change request was not raised because this was considered a low-risk operation and was difficult to foresee the failure caused by the missing DNS record.
Incident severitySeverity: CRITICAL
Data loss: NO
Timeline
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In future, even the low-risk operations on critical services such as HA Proxy should be carried out in the planned manner and out of business hours.
Identify the root cause of the communication gap between IT & SWD for regarding the missing DNS record with help from IT and take appropriate action.