An LDAP directory has entries that contain information pertaining to entities. Each attribute has a name and one or more values. The names of the attributes are mnemonic strings, such as cn for common name, or mail for email address. For example, a company may have an employee directory.

The Common Name (CN), also known as the Fully Qualified Domain Name (FQDN), is the characteristic value within a Distinguished Name (DN). Typically, it is composed of Host Domain Name and looks like, "www.digicert.com" or "digicert.com". The Common Name field is often misinterpreted and is filled out incorrectly.

A DN has a unique name that identifies the entry at the respective hierarchy. In the example above, John Doe and Jane Doe are different common names (cn) that identify different entries at that same level. A DN is also a fully qualified path of names that trace the entry back to the root of the tree.