ACP-Cloud1 ACP Cloud Computing Certification Questions and Answers

Once a VPC is created in Alibaba Cloud, its CIDR Block cannot be modified. This design ensures stability and network consistency within the VPC. To change the network range, a new VPC would need to be created with the desired CIDR Block.

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According to the Alibaba Cloud ECS documentation1, the Pay-As-You-Go billing method is flexible and suitable for short-term or uncertain workloads. However, it is also the most expensive option compared to other billing methods. To reduce the cost of Pay-As-You-Go instances, you can purchase a Savings Plan, which is a discount plan that offers lower prices for a fixed amount of hourly usage. A Savings Plan can be applied to any Pay-As-You-Go instance in the same region, regardless of the instance type, operating system, or zone. Therefore, option A is the most cost-effective billing method for a 10-day test, as it allows you to enjoy the flexibility of Pay-As-You-Go and the savings of a fixed commitment. References: Billing methods and Savings Plan.

Alibaba Cloud RDS allows multiple databases to be created on a single instance. However, each database within the same instance must have a unique name, and resources are shared among instances unless specified otherwise. Additionally, not all RDS editions support High Availability (HA) mode; HA is typically available in certain editions, like RDS for MySQL and RDS for PostgreSQL.

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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