VM-Series firewalls and hardware firewalls that are external to the Kubernetes cluster are problematic for protecting containerized workloads because they are located outside the cluster and have no visibility into application-level cluster traffic. Kubernetes is a platform that provides orchestration, automation, and management of containerized applications. Kubernetes cluster traffic consists of traffic between containers within a pod, across pods, or across namespaces. VM-Series firewalls and hardware firewalls that are external to the Kubernetes cluster cannot inspect or control this traffic, as they only see the encapsulated or aggregated traffic at the network layer. This creates blind spots and security gaps for containerized workloads. VM-Series firewalls and hardware firewalls that are external to the Kubernetes cluster are not problematic for protecting containerized workloads because they do not scale independently of the Kubernetes cluster, are managed by another entity when located inside the cluster, or function differently based on whether they are located inside or outside of the cluster, as those are not valid reasons or scenarios for firewall deployment in a Kubernetes environment. Reference: Palo Alto Networks Certified Software Firewall Engineer (PCSFE), [CN-Series Concepts], [VM-Series on Kubernetes]