In accordance with the requirements of the CA / Browser Forum starting 8 September 2017, SSL certificate issuers will verify the CAA records in the DNS records of clients applying for SSL certificates.
If you enter a specific CA name, only the Certificate Authorities will be able to issue the certificate.
If you run a online business, you are sure to use Google AdWords. Perhaps this is one of the main traffic sources on your site, so the last message you want to see is "Your account has been suspended ...". And yet, you can expect it if your site is not SSL-secured.
Starting 1st of August 2016, Comodo and DomenySSL will no longer offer SGC variants of certificates. As your account has a valid SGC certificate which will be up for renewal in the future, the company has prepared a list of recommended alternatives.
Thawte is only one of the few vendors outside of the United States. As the main competitor of American vendors quickly gained a 40 % share of the market SSL certificates.