"To prevent browser warnings, use an SSL certificate with a common name or subject alternative name that contains the fully-qualified domain name of the server that hosts the certificate."
If the domain name (FQDN) in the TLS/SSL certificate doesn't match exactly the domain name displayed in the address bar of the browser, the browser stops the connection to the website and displays a name mismatch error. Errors create mistrust when connecting to a site and can cause clients to avoid your site (see Name Mismatch in Web Browser).
When you order a TLS/SSL certificate, the domain name on the TLS/SSL certificate must match the domain name for the website shown in the address bar of the browser exactly. For example, to get a certificate for www.example.com, you must add www.example.com as a common name or SANs (FQDN) in the order form.
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