The format in which you will need to enter your common name (i.e. domain name) when generating your CSR will vary depending on the type of certificate you are using it for. Entering your common name in the correct format will prevent you from running into issues when you generate/enroll your order after purchase, as CSRs with incorrect formats can cause errors and prevent your certificate from being issued.
Refer to the chart below to determine how your common name should be entered depending on the type of SSL Certificate you have purchased.
*In the case of the Multi-Domain Wildcard, even though the certificate will cover multiple wildcard SANs, the common name listed in the CSR must be a fully-qualified domain name (FQDN), and therefore cannot have the wildcard asterisk (*). All of the SANs, however, can either be FQDNs or wildcards.
When generating a CSR for multi-domain certificates, it is also important to note that you should not enter your SANs (Subject Alternative Name – these are the additional domains your SSL certificate will also cover, thus the name “multi-domain,”) into the common name in the CSR. Your common name should just be one website, formatted as indicated above, and in cases of a multi-domain certificate, will be the main domain identified in the certificate details.