/Recent content in About on Corentin DupaigneHugoenTue, 22 Sep 2026 00:00:00 +0000/journal/how-does-a-clusterip-actually-work/Tue, 22 Sep 2026 00:00:00 +0000/journal/how-does-a-clusterip-actually-work/<p>A ClusterIP is a Kubernetes resource that associates a stable virtual IP to a set of pods (a Service&rsquo;s endpoints). It is a dumb entity. A load balancer (usually kube-proxy) then redirects the packet to the real IP of one of the pod replicas. By default the packet is redirected to a random replica with no preference, with a probability of 1/N (N being the number of replicas).</p> <figure> <img src="20260922-174207.png" alt="ClusterIP virtual IP distributing traffic to pod replicas" width="688" height="677" style="--w: 688px" class="is-light" loading="lazy" decoding="async" /> </figure><h2 id="behind-the-scenes">Behind the scenes<a class="heading-anchor" href="#behind-the-scenes" aria-label="Link to this section">#</a></h2> <p>Because the ClusterIP is a dumb entity it cannot redirect the packets to its pods. So how does kube-proxy handle the load balancing, service → pod?</p>