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KodeCloud CKA Cluster Networking

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Cluster Networking

  • The nodes (master & worker) must have atleast one interface connected to an network.
    • The interface must have an IP address configured.
  • The nodes must have a unique host name and mac address.
  • The master should accept connections on port 6443 for the API server.
  • The kubelets on the master and the worker node is on port 10250.
  • Kube-scheduler requires port 10251 to be open.
  • Kube-controllermanager requires port 10252 to be open.
  • Worker nodes expose services for external access so ports 30000 - 32767 should be open.
  • Etcd server listens on port 2379.
  • If we have multiple masters then all these ports should be open on all the masters.
    • Additionally port 2380 should be open so that etcd clients can communicate with each other.
  • Cluster networking diagram:
    • attachments/Pasted image 20230529140405.jpg
  • Port requirement table:
    • attachments/Pasted image 20230529140505.jpg
The ports mentioned must be whitelisted if we are setting up k8s networking ourselves.

If things are not working then this is one place to look for.

Last updated: 2023-05-29