This topic describes the domain names that support or do not support SSL certificates.

Alibaba Cloud CDN imposes no limits on domain names that support SSL certificates. After you configure an SSL certificate for a domain name and enable HTTPS, data transmission between clients and edge nodes is encrypted. This improves the security of data transmission and prevents data leaks and tampering. We recommend that you enable HTTPS for the transmission of sensitive data such as user accounts and identities. HTTPS cannot be enabled if you do not configure an SSL certificate. If HTTPS is disabled, data is transmitted as plaintext between clients and edge nodes. This reduces data security and raises risks such as data leaks and tampering.