EKS networking with VPC CNI in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the VPC CNI plugin in Amazon EKS?

The VPC CNI plugin allows Kubernetes pods to have IP addresses from the VPC network, enabling them to communicate directly with other AWS resources using native VPC networking.

beginner

How does the VPC CNI plugin assign IP addresses to pods?

It assigns each pod an IP address from the VPC subnet, just like an EC2 instance, so pods can communicate directly with other resources in the VPC without NAT.

intermediate

Why is it important to have enough free IP addresses in your VPC subnets when using VPC CNI?

Because each pod gets its own IP from the subnet, running many pods can exhaust available IPs, causing pods to fail to start due to lack of IP addresses.

intermediate

What is the benefit of using VPC CNI over other Kubernetes networking plugins in EKS?

VPC CNI provides high performance and native AWS networking features, such as security groups and routing, making pod networking seamless with AWS infrastructure.

advanced

How can you scale the number of pods in EKS without running out of IP addresses with VPC CNI?

You can add more subnets with additional IP ranges or use features like 'prefix delegation' to allocate larger blocks of IPs to nodes, increasing available pod IPs.

What does the VPC CNI plugin assign to each Kubernetes pod in EKS?

A An IP address from the VPC subnet

B A private IP from a separate Kubernetes network

C A public IP address

D No IP address, uses node IP

VPC CNI assigns each pod an IP address from the VPC subnet, allowing direct communication within the VPC.

Why might pods fail to start when using VPC CNI in EKS?

A Because the cluster is out of CPU resources

B Because there are no free IP addresses in the subnet

C Because pods need public IPs

D Because the VPC CNI plugin is disabled

Pods need IP addresses from the subnet; if none are free, pods cannot get an IP and fail to start.

Which AWS resource's IP range does VPC CNI use for pod IPs?

A Elastic IP pool

B Internet Gateway IPs

C VPC subnet CIDR block

D AWS Lambda IP range

VPC CNI uses the VPC subnet CIDR block to assign IPs to pods.

What is a common way to increase available pod IPs in an EKS cluster using VPC CNI?

A Use public IPs for pods

B Add more nodes without changing subnets

C Disable VPC CNI plugin

D Add more subnets with larger CIDR blocks

Adding subnets with more IP addresses increases the pool of IPs available for pods.

What networking feature does VPC CNI enable for pods in EKS?

A Pods have native VPC networking with security groups

B Pods cannot communicate outside the cluster

C Pods use NAT to access the internet

D Pods share node IP addresses

VPC CNI allows pods to have native VPC networking, including security group integration.

Explain how the VPC CNI plugin manages pod networking in an EKS cluster.

Think about how pods connect to other AWS services and the IP addresses they use.

Describe strategies to avoid IP exhaustion when using VPC CNI in EKS.

Consider how IP addresses are allocated and ways to increase their availability.