The fastest way to switchover is probably adding a iptables rule on the old server to DNAT to the new server. Unless you have a load-balancer or another network

The fastest way to switchover is probably adding a iptables rule on the old server to DNAT to the new server. Unless you have a load-balancer or another network middleware like Kubernetes' clusterIP services (which uses iptables or IPVS internally). Waiting for a rolling restart or DNS cache expiration could take a while, during which the app is talking to a read-only database, if I understand correctly.