An Anti-DDoS Premium Mainland China Acceleration (MCA) instance can be used with an Anti-DDoS Premium Insurance Plan or Unlimited Plan instance to accelerate access to your services that are deployed outside mainland China.
Prerequisites
Background information
After you configure an Anti-DDoS Premium MCA instance that is used with an Anti-DDoS Premium Insurance Plan or Unlimited Plan instance, the instance protects your services. If no DDoS attacks are launched, the Anti-DDoS Premium MCA instance accelerates web access to your services. Otherwise, the Anti-DDoS Premium Insurance Plan or Unlimited Plan instance automatically takes over to mitigate DDoS attacks against your services.
For more information about the scenarios to which MCA applies, see Scenarios of Anti-DDoS Premium.

You can configure an Anti-DDoS Premium MCA instance for a domain name (Layer 7) or service port (Layer 4).
After you purchase Anti-DDoS Premium MCA and Insurance Plan or Unlimited Plan instances, add your domain name or service port to the instances in the Anti-DDoS Premium console. Then, configure a Sec-Traffic Manager rule to enable the auto-switching between an Anti-DDoS Premium MCA instance and an Anti-DDoS Premium Insurance Plan or Unlimited Plan instance. This rule forwards non-attack traffic to the origin server of your web service.