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Visual Walkthrough · Kubernetes networking

How CoreDNS Works on Amazon EKS

Follow web's lookups of shop and api.stripe.com through CoreDNS and out to the VPC resolver, then check yourself with 8 questions.

1Visual Walkthrough

A Pod's DNS lookups traced through the kube-dns Service, the CoreDNS Pods and the VPC resolver on EKS A VPC with three nodes. node-1 runs the web Pod and shows its resolv.conf; node-2 and node-3 run the CoreDNS Pods. The Kubernetes API holds the kube-dns Service (172.20.0.10) and Service shop (172.20.14.7). The VPC resolver at 10.0.0.2 forwards public names to the internet. The walkthrough shows search-domain expansion, CoreDNS answering with the ClusterIP, ndots:5 wasting queries for api.stripe.com, the 1,024 packets per second per-ENI limit, NodeLocal DNSCache and CoreDNS autoscaling. VPC · 10.0.0.0/16 · us-west-2 node-1 · 10.0.1.10 web Pod 10.0.1.22 · namespace default web's /etc/resolv.conf nameserver 172.20.0.10 search default.svc.cluster.local svc.cluster.local cluster.local us-west-2.compute.internal node-local-dns DaemonSet · 169.254.20.10 a DNS cache on every node coredns-c 10.0.1.53 · added by the autoscaler node-2 · 10.0.2.10 coredns-a 10.0.2.53 · kube-system node-3 · 10.0.3.10 coredns-b 10.0.3.53 · kube-system VPC resolver 10.0.0.2 Amazon- ProvidedDNS VPC base +2 KUBERNETES API Service kube-dns namespace kube-system ClusterIP 172.20.0.10 · :53 Service shop namespace default ClusterIP 172.20.14.7 DNS name: shop.default.svc.cluster.local Public DNS api.stripe.com answered by Stripe's name servers

    2Quiz to check understanding

    Check yourself