Home / Technology / Kubernetes Myth #09: ClusterIP Services Always Use Round-Robin Load Balancing

Kubernetes Myth #09: ClusterIP Services Always Use Round-Robin Load Balancing

Myth: Kubernetes ClusterIP Services always distribute traffic using a round-robin algorithm.

Reality: The default iptables mode of kube-proxy does not use round-robin. Instead, it uses random probability-based selection for load balancing.

🔍 How It Actually Works:

  • kube-proxy sets up NAT rules using iptables.

  • When a request hits a ClusterIP, iptables randomly selects one of the backend pods.

  • The selection is not true round-robin but statistically distributed.

🔥 Want True Round-Robin?

✅ Use kube-proxy in IPVS mode:

Supports round-robin (rr), least connections (lc), and other scheduling methods.

Enable it with:

kube-proxy –proxy-mode=ipvs

✅ Use an external load balancer (e.g., NGINX, HAProxy) if strict round-robin is needed.

🚀 Kubernetes is full of surprises—what other myths have you encountered? Drop them in the comments!

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