CNAME
If you use DigiCert as your Certificate Authority (CA), you can complete DCV with a special CNAME record.
Since this method is only available using the API, you need to make a POST request and set a "method":"cname" parameter.
Within the ssl object in the response, refer to the values present in the validation_records array. Each record will contain a property for cname and cname_target (you can also access these values in the dashboard by clicking that specific hostname certificate). Provide these values to your customer so they can add a CNAME record at their authoritative DNS provider.
If you would like to request an immediate recheck, rather than wait for the next retry, send a PATCH request with the same values as your initial POST request.