ACP-Cloud1 Exam Dumps : ACP Cloud Computing Certification

To isolate ECS instances within different VSwitches in a VPC while allowing them to access the internet and other intranet resources, each VSwitch's instances should be in separate Security Groups. By configuring each group to allow all VPC CIDR blocks first and then restricting access to other VSwitch CIDR blocks with a higher priority rule, instances in each VSwitch are isolated without affecting the VPC's external connections. This approach follows Alibaba Cloud's Security Group best practices and CIDR-based access control within VPC environments.

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When the black hole policy is triggered by excessive DDoS traffic, the affected server is temporarily isolated from the network to prevent further damage. During this period, no services are available, meaning the server cannot provide limited-speed services.

According to the Alibaba Cloud Academy, a VPC is an isolated network environment that is completely isolated from each other. Each VPC has an independent tunnel ID, and a tunnel ID corresponds to a virtualized network. This means that different VPCs cannot communicate with each other through the tunnel ID. Subnets are not divided like the traditional network environment, but rather are logical divisions of the VPC. Different cloud servers within each subnet are connected by the same router, but different subnets are interconnected by route tables, not switches. ECS instances in a VPC use security group firewalls for Layer 4 network access control, not Layer 2. The internal networks of different VPCs are completely isolated and can be interconnected through IP addresses mapped to the outside, such as NAT Gateway or EIP. References: ACP Cloud Computing Certification Preparation Course - Internetworking with VPC, Alibaba Cloud VPC User Guide