If blackhole filtering is triggered on a server that encounters DDoS attacks, access to the public IP address of the server is blocked for a specific duration and resumes after the duration expires. The default duration of blackhole filtering varies based on the region where an asset resides. The actual duration varies based on the severity of attacks that the asset encounters. You can view the actual duration for your asset in the Anti-DDoS console.
Background information
For more information about the blackhole filtering policy of Alibaba Cloud, see Blackhole filtering policy of Alibaba Cloud.