CKA, CKAD, and CKS were created by The Linux Foundation and the Cloud Native Computing Foundation (CNCF) as a part of their ongoing effort to help develop the Kubernetes ecosystem. The exams are online, proctored, and performance-based which requires solving multiple tasks from a command line running Kubernetes. CKS is a performance-based certification exam that tests candidates' knowledge of Kubernetes and cloud security in a simulated, real world environment. Candidates must have taken and passed the Certified Kubernetes Administrator (CKA) exam prior to attempting the CKS exam. CKS may be purchased but not scheduled until CKA certification has been achieved.
The CKA certification is for Kubernetes administrators, cloud administrators and other IT professionals who manage Kubernetes instances. A CKAD exam is for IT professionals building, deploying, and configuring cloud native applications with Kubernetes. And a Certified Kubernetes Security Specialist (CKS) is an accomplished Kubernetes practitioner (must be CKA certified) who has demonstrated competence on a broad range of best practices for securing container-based applications and Kubernetes platforms during build, deployment and runtime.