The image shows an OCI Region with a VCN across three Availability Domains. The VCN contains a:

LB Subnet with a Public Load Balancer.
OKE Nodes Subnet with an OKE Cluster having an Arm Pool and Preemptible Pool.
The Arm Pool consists of : Availability Domain 1: Jenkins Controller A and Volume, Availability Domain 2: Jenkins Controller B and Volume, Availability Domain 3: Jenkins Controller C and Volume.

The Preemptible Pool consists of: Availability Domain 1: Agent C1 and Agent B2, Availability Domain 2: Agent A1 and Agent C2, Availability Domain 3: Agent A2 and Agent B1.

Internet Teams connect to the Public Load Balancer in the LB Subnet.