= k8s/StudyNotes/ k8s DNS =

 * Pods & Services
   * Services.
     * DNS: <Hostname>.<Namespace>.<Type>.<Root=cluster.local>
       * e.g. web-service.appsNs.svc.cluster.local

   * Pods, do not get dns entries by default, can be enabled.
     * If pod dns enabled, creates record from ip 10.244.2.5 -> 10-244-2-5.appsNs.pod.cluster.local

   * In same namespace web-service.
   * In apps namespace apps.web-service

 * in container, /etc/resolve.conf, has k8s dns server as nameserver
   * kubelet launches pods and does the /etc/resolve.conf setup.
     * adds to /etc/resolve.conf nameserver and for ns=default e.g '''search default.svc.cluster.local svc.cluster.local cluster.local'''

 * CoreDNS (Service kube-dns)
  * From v1.12 CoreDNS used for dns, deployed as pod in -n kube-system
     * config /etc/coredns/Corefile, passed into pod as '''configmap''' coredns.
     * uses plugins