The Common Name (CN), also known as the Fully Qualified Domain Name (FQDN), is the characteristic value within a Distinguished Name. Typically, it is composed of Host Domain Name and looks like, "www.symantec.com" or "symantec.com". The Common Name field is often misinterpreted and is filled out incorrectly. Do not use your organization's actual name as your common name.
Before you can enroll for a certificate, you must generate a Certificate Signing Request (CSR) from your Web server. While generating a CSR, you type information in the Common Name field.
Certificates are specific to the Common Name that they have been issued to at the Host level. The Common Name must be the same as the Web address you access when connecting to a secure site. For example, a Server ID for the domain "symantec.com" will receive a warning if accessing a site named "www.symantec.com" or "secure.symantec.com" because "www.symantec.com" and "secure.symantec.com" are different from the CN, "symantec.com". In this case, you must create a CSR for the correct Common Name to resolve the problem.
Code Signing ID's
The Common Name for Code Signing ID's is not related to a Fully Qualified Domain Name (FQDN) and should be identical to the Organization Name. Code Signing ID's are for digitally signing code and do not utilize any specific URL's.