DNS¶

OpenShift requires specific DNS records for the API and ingress services. All records must be resolvable before installation begins.

Required DNS Records¶

A Record	Value
api.{{ cluster_name }}.{{ base_domain }}	API VIP or node IP (SNO)
api-int.{{ cluster_name }}.{{ base_domain }}	API VIP or node IP (SNO)
*.apps.{{ cluster_name }}.{{ base_domain }}	Ingress VIP or node IP (SNO)

Validate the DNS using dig:

dig +noall +answer @{{ nameserver_ip }} api.{{ cluster_name }}.{{ base_domain }}
dig +noall +answer @{{ nameserver_ip }} test.apps.{{ cluster_name }}.{{ base_domain }}

Details¶

API Records¶

The api record is used by external clients (developers, CI/CD) to reach the Kubernetes API. The api-int record is used by cluster nodes internally. Both should resolve to the same API VIP.

Wildcard Ingress¶

The *.apps wildcard record routes all application traffic through the OpenShift router. This must resolve to the ingress VIP.

Single Node OpenShift (SNO)¶

For SNO, all three DNS records point to the single node's IP address. No VIPs are needed.

Reverse DNS (PTR Records)¶

Node A records (for example cp01.{{ cluster_name }}.{{ base_domain }}) and reverse DNS (PTR) are recommended, not required for installation. Without PTR records, nodes may register with incorrect hostnames during provisioning.

dig +noall +answer -x {{ node_ip }}

Each node IP should resolve back to its FQDN (e.g., cp01.{{ cluster_name }}.{{ base_domain }}).

Note

Wildcard DNS records may require special handling in Active Directory DNS. Consult your DNS administrator if using AD-integrated DNS.