This topic provides answers to some commonly asked questions about the billing of burstable protection provided by Anti-DDoS Proxy (Chinese Mainland).
If no attacks are detected, are burstable protection fees charged?
No, if no attacks are detected, no burstable protection fees are charged. Only subscription fees for basic protection are charged.
If I purchase an Anti-DDoS Proxy (Chinese Mainland) instance with a basic protection bandwidth of 20 Gbit/s and a burstable protection bandwidth of 50 Gbit/s, what is the maximum mitigation capacity?
The maximum mitigation capacity is determined by the burstable protection bandwidth, which is 50 Gbit/s in this example. If you purchase a burstable protection bandwidth of 20 Gbit/s that equals the basic protection bandwidth, the maximum mitigation capacity is 20 Gbit/s. In this case, your Anti-DDoS instance does not provide burstable protection.
What happens if the size of DDoS attacks exceeds the burstable protection bandwidth?
If the size of DDoS attacks exceeds the burstable protection bandwidth, the traffic that is destined for the protected IP addresses is forwarded by using null routes.
If the basic protection bandwidth is 30 Gbit/s, the burstable protection bandwidth is 50 Gbit/s, and the inbound bandwidth s is 45 Gbit/s, how is burstable protection charged?
Burstable protection is charged based on the difference between the inbound bandwidth and the basic protection bandwidth. In this example, you are charged only for the burstable protection bandwidth of 15 Gbit/s at the price of USD 330/day. For more information, see Billing of the burstable protection bandwidth feature.
Can I change the burstable protection bandwidth from 100 Gbit/s to 200 Gbit/s?
Yes, you can change the burstable protection bandwidth from 100 Gbit/s to 200 Gbit/s.
You can manage burstable protection for an Anti-DDoS Proxy (Chinese Mainland) instance on the Instance Management page in the Anti-DDoS Proxy (Chinese Mainland) console. 
If burstable protection on the day when you change the burstable protection bandwidth is already charged, the system starts to charge burstable protection based on the newly selected bandwidth the next day.
If the basic protection bandwidth of 30 Gbit/s provided by the Anti-DDoS Proxy (Chinese Mainland) instance cannot meet my requirements, can I increase the protection bandwidth anytime?
Yes, you can increase the basic protection bandwidth or burstable protection bandwidth.
Increase the basic protection bandwidth
You can increase the basic protection bandwidth for an Anti-DDoS Proxy (Chinese Mainland) instance on the Instances page in the Anti-DDoS Proxy (Chinese Mainland) console and complete the payment. For more information, see Upgrade an instance.
Increase the burstable protection bandwidth
You can manage burstable protection for an Anti-DDoS Proxy (Chinese Mainland) instance on the Instance Management page in the Anti-DDoS Proxy (Chinese Mainland) console. Burstable protection is billed on a pay-as-you-go basis and charged based on the difference between the peak traffic throughout of DDoS attacks and the basic protection bandwidth. For more information, see Billing of the burstable protection bandwidth feature.
If an IP address is attacked multiple times in a day, how is the mitigation fee calculated?
Burstable protection is charged only once based on the peak traffic throughout of DDoS attacks on the same day (from 00:00 to 24:00). For example, if three DDoS attacks are launched to a protected IP address, and the peak traffic throughout of the three DDoS attacks are 50 Gbit/s, 100 Gbit/s, and 200 Gbit/s, burstable protection is charged based on the highest peak traffic throughput (200 Gbit/s).
How do I prevent an Anti-DDoS Proxy (Chinese Mainland) instance from providing burstable protection?
You can set the burstable protection bandwidth and basic protection bandwidth to the same value. If DDoS attacks exhaust the basic protection bandwidth, no burstable protection is provided to mitigate the attacks and no bills are generated for burstable protection.
You can manage burstable protection for an Anti-DDoS Proxy (Chinese Mainland) instance on the Instance Management page in the Anti-DDoS Proxy (Chinese Mainland) console.