DNS Server upstream maintenance mode momentarily in OpenShift Container Platform 4 with CoreDNS Failover
Issue
The network team is planning to upgrade internal upstream DNS servers. These servers are referenced in the resolv.conf of OpenShift nodes. The concern is whether CoreDNS will automatically switch to the secondary DNS server when the primary server is temporarily unavailable during the upgrade.
Environment
- Red Hat OpenShift Container Platform: v4.x [RHOCP]
- CoreDNS: v1.8.x
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