1. To prevent Horizon clients and admins from receiving errors or alerts about untrusted certificates.
2. They will receive an error message stating that the certificate name does not match the hostname, or that the certificate is not trusted.
3. The certificate has the Friendly Name set to vdm.
4. Subject Alternative Names (SAN).
5. Yes.
6. Potential security concerns since the certificate contains additional hostnames that do not match the server name; that certificate could be used elsewhere and clients would trust it.