DNS Requirements

DNS is used for name resolution and reverses name resolution. DNS A/AAAA or CNAME records are used for name resolution and PTR records are used for reverse name resolution. The reverse records are important because Fedore CoreOS (RHCOS) uses the reverse records to set the hostname for all the nodes. Additionally, the reverse records are used to generate the certificate signing requests (CSR) that OKD needs to operate.

The following DNS records are required for an OKD cluster that uses user-provisioned infrastructure. In each record, <cluster_name> is the cluster name and <base_domain> is the cluster base domain that you specify in the install-config.yaml file. A complete DNS record takes the form: <component>.<cluster_name>.<base_domain>..

Component Record Description
Kubernetes API api.<cluster_name>.<base_domain>. Add a DNS A/AAAA or CNAME record, and a DNS PTR record, to identify the load balancer for the control plane machines. These records must be resolvable by both clients external to the cluster and from all the nodes within the cluster.
api-int.<cluster_name>.<base_domain>. Add a DNS A/AAAA or CNAME record, and a DNS PTR record, to identify the load balancer for the control plane machines. These records must be resolvable from all the nodes within the cluster.
Routes *.apps.<cluster_name>.<base_domain>. Add a wildcard DNS A/AAAA or CNAME record that refers to the load balancer that targets the machines that run the Ingress router pods, which are the worker nodes by default. These records must be resolvable by both clients external to the cluster and from all the nodes within the cluster.
Bootstrap bootstrap.<cluster_name>.<base_domain>. Add a DNS A/AAAA or CNAME record, and a DNS PTR record, to identify the bootstrap machine. These records must be resolvable by the nodes within the cluster.
Master hosts <master><n>.<cluster_name>.<base_domain>. Add DNS A/AAAA or CNAME records and DNS PTR records to identify each machine for the master nodes. These records must be resolvable by the nodes within the cluster.
Worker hosts <worker><n>.<cluster_name>.<base_domain>. Add DNS A/AAAA or CNAME records and DNS PTR records to identify each machine for the worker nodes. These records must be resolvable by the nodes within the cluster.
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