If reverse lookup fails due to an error, such as reverse lookup services being down, WMCO does not fall back to using the VM hostname to determine if a CSR should be approved.    

    Always

    1. Deploy WMCO in an environment without DNS reverse lookup
    2. Add a BYOH instance using an IP address in the windows-instances configmap
    

    Node CSR is not approved, WMCO logs contain:

2024-07-03T20:46:59Z	ERROR	Reconciler error	{"controller": "certificatesigningrequest", "controllerGroup": "certificates.k8s.io", "controllerKind": "CertificateSigningRequest", "CertificateSigningRequest": {"name":"csr-bttwq"}, "namespace": "", "name": "csr-bttwq", "reconcileID": "35e34aa1-6946-4cfb-a8f0-84ee34eb31a1", "error": "WMCO CSR Approver could not approve CSR csr-bttwq: error determining if CSR csr-bttwq should be approved: error validating node name winhost-a6okf for CSR: csr-bttwq: unable to map node name to the addresses of Windows instances: failed to lookup DNS for IP 10.95.108.42: lookup 42.108.95.10.in-addr.arpa. on 172.30.0.10:53: no such host"}

    Node CSR is approved, Windows node is schedulable

QE can test this with regression testing only.