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Difficulty: MediumConfigure Azure Kubernetes Service (AKS)

An administrator plans to deploy a new Azure Kubernetes Service (AKS) cluster named aks-shipping. The corporate network team has allocated a single subnet with the address space 192.168.10.0/25192.168.10.0/25 for the cluster. The cluster is expected to scale to a maximum of 2020 nodes, and each node must support up to 3030 pods. The pods do not require direct IP address visibility from the virtual network, but they must be able to access external resources. Which network configuration should the administrator select for the cluster to prevent IP address exhaustion?

  1. A
    Azure CNI
  2. kubenetAnswer
  3. C
    Azure CNI with dynamic pod IP allocation
  4. D
    Azure CNI with a Basic Load Balancer

Answer

Configure the AKS cluster to use the kubenet network model.
The correct option is kubenet. The kubenet network model only assigns IP addresses to the AKS nodes from the virtual network subnet. Pods receive IP addresses from a separate, internal address range and use NAT to access resources outside the cluster. For 2020 nodes, this requires only 2020 IP addresses (plus a few for upgrade operations), which easily fits within the 128128 IP addresses (123123 usable) provided by the 192.168.10.0/25192.168.10.0/25 subnet.

Step-by-Step Solution

1
Calculate the available IP addresses in the subnet.
A 192.168.10.0/25192.168.10.0/25 subnet provides 128128 IP addresses, with 123123 usable after Azure reserves 55 addresses.
This establishes the IP address constraint of the physical subnet hosting the cluster nodes.
2
Calculate the IP address requirement for Azure CNI.
For 2020 nodes running 3030 pods each, Azure CNI requires a minimum of 20×(30+1)=62020 \times (30 + 1) = 620 IP addresses from the subnet.
Azure CNI pre-allocates VNet IP addresses to every pod, which will cause IP address exhaustion in the /25/25 subnet.
3
Calculate the IP address requirement for kubenet.
For 2020 nodes, kubenet only allocates node IPs from the subnet, requiring approximately 2121 IP addresses (including upgrade margin). Pods use an internal private IP range.
This shows that kubenet fits safely within the 123123 usable IP addresses of the /25/25 subnet.

Key Concept

Azure Kubernetes Service network model selection based on IP address capacity constraints.
Estimated Time:1m 30s
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Topics

Configure Azure Kubernetes Service (AKS)

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