I want to secure one domain
To secure 1 domain choose a standard EV certificate.
Comodo, GlobalSign and GeoTrust add a free extra domain to their single domain certificates. If the certificate is ordered for a “www.” domain, the variant without “www.” is added for free. The certificate will then be valid for both domains – with and without “www.”
SSLCheck
Our SSLCheck will examine your website's root and intermediate certificates for correctness and report any potential issues