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Why Does Physical Isolation in AKS Reduce Pod Density Compared to Logical Isolation?
Understand the trade-offs between physical and logical isolation in AKS for AZ-500 exam. Learn why physical isolation using dedicated nodes provides strong security but results in lower pod density compared to logical isolation methods like network policies and namespaces.
Question
Physical isolation in AKS provides the highest pod density for running workloads.
A. TRUE
B. FALSE
Answer
B. FALSE
Explanation
The statement is B. FALSE. Physical isolation in AKS provides the strongest security boundary but results in the lowest pod density, as it prevents efficient sharing of node resources across different workloads.
Separate physical nodes result in lower pod density and greater management overhead.
Understanding Physical vs. Logical Isolation in AKS
The core of this concept lies in the trade-off between security isolation and resource utilization.
Physical Isolation
Physical isolation means dedicating entire compute nodes to a specific application, service, or tenant. In AKS, this is typically achieved by creating separate node pools.
- How it works: You can use node taints and pod tolerations to ensure that only specific pods are scheduled onto the nodes in a dedicated pool. This creates a hard boundary, guaranteeing that one workload’s processes cannot interfere at the kernel or hardware level with another’s.
- The Security Benefit: This is the highest level of isolation possible within a Kubernetes cluster. It is often used for highly sensitive workloads, multi-tenant environments with strict separation requirements, or applications with specific hardware needs (like GPU nodes).
- The Density Problem: Because a node is dedicated to a single workload, its resources (CPU, memory) are not shared. If that workload is not resource-intensive or has periods of low activity, the node’s resources are wasted. You cannot “fill up” the remaining space on the node with pods from other applications. This leads to lower overall pod density, requiring more nodes to run the same number of total pods, which increases costs and management overhead.
Logical Isolation for Higher Density
To achieve high pod density, you use logical isolation, where pods from multiple different applications share the same nodes.
- How it works: Kubernetes provides several mechanisms to logically separate workloads running on the same infrastructure:
- Namespaces: Isolate resources at the API level, preventing naming conflicts and providing a scope for access control.
- Network Policies: Act as a micro-firewall for pods, controlling which pods can communicate with each other over the network.
- Pod Security Admission (or deprecated Pod Security Policies): Enforce baseline security standards on pods, restricting their capabilities and what they can do on the host node.
- The Density Benefit: By allowing multiple workloads to share nodes, you can pack pods more efficiently, maximizing the utilization of each node’s resources. This leads to higher pod density and lower costs.
In summary, you choose physical isolation for maximum security at the cost of efficiency and pod density. You choose logical isolation to maximize pod density and resource utilization while relying on Kubernetes’ software-based controls to provide security.
Microsoft Certified Azure Security Engineer Associate AZ-500 certification exam assessment practice question and answer (Q&A) dump including multiple choice questions (MCQ) and objective type questions, with detail explanation and reference available free, helpful to pass the Microsoft Certified Azure Security Engineer Associate AZ-500 exam and earn Microsoft Certified Azure Security Engineer Associate AZ-500 certification.