Refer to the exhibit. A four-node APIC cluster is deployed across two data centers. What happens to the database shards when DC1 with APIC1 and APIC2 fail?

If green and red were inaccessible, it implies no replicas are available or even read-only access is impossible, which is not necessarily the case when replicas exist on surviving APICs.

The blue shard would remain primary, but green and red cannot become standby; they would either be read-only or inaccessible due to primary loss and lack of quorum for election.

In a 4-node APIC cluster, losing two nodes (APIC1 and APIC2) means the cluster lacks the necessary quorum (3 nodes) for full operational capability and new primary elections. The blue shard's primary must reside on a surviving APIC (APIC3 or APIC4), allowing it to remain in read-write mode. However, the green and red shards, having lost their primary instances in the failed DC1, cannot elect new primaries due to insufficient quorum and thus become accessible only in read-only mode from their surviving replicas.

The red shard cannot become primary because its primary node failed, and with only two APICs remaining, there is insufficient quorum to elect a new primary for the red shard.