Yes. You will be billed according to your daily elastic protection bandwidth range. See Billing Overview for more billing details.
For example, suppose you bought an Anti-DDoS Advanced instance with 20 Gbps base protection bandwidth and 50 Gbps elastic protection bandwidth. Suppose your instance experienced a DDoS attack on one day with 45-Gbps peak traffic flow, which exceeded the base protection bandwidth limit and therefore activated elastic protection. 45 Gbps falls within the 40 Gbps to 50 Gbps range and your elastic charge for that day will be based on the range.
No. According to the billing model mentioned above, and because your IP is automatically blocked when the attack traffic exceeded the elastic protection bandwidth, you only need to pay for the difference between the base protection bandwidth limit and the elastic protection bandwidth limit. The amount of traffic that exceeds the elastic protection bandwidth limit will not be calculated.
No. In such cases, no additional elastic defense service fees will apply.
No. You can increase, but not decrease your base protection bandwidth.
Yes. You can increase and decrease elastic protection bandwidth on the Anti-DDoS Advanced Basic Info page. The available options vary by region. For details, please see Product Overview.
If you have already been billed for attack traffic when you made the adjustment, you will be billed based on the new plan starting the next day.
The Anti-DDoS Advanced service is billed based on the peak attacking traffic during the day and for once only.
You need to pay for the instances separately if both of them have exceeded their base protection bandwidth limits.