ACP-Cloud1 Exam Dumps : ACP Cloud Computing Certification

According to the Alibaba Cloud Auto Scaling documentation1, the Lifecycle Hook feature allows you to perform custom operations on instances that are added to or removed from a scaling group. You can define a lifecycle hook to specify a timeout period and a web hook URL. When an instance is about to be removed, Auto Scaling sends a notification to the web hook URL and waits for a response. During the timeout period, you can perform the necessary operations on the instance, such as gracefully shutting down the service, backing up the data, or sending a custom notification. After the operations are completed, you can send a response to the web hook URL to confirm the removal of the instance. This way, you can ensure that the instance is removed without affecting the user experience or causing data loss. Therefore, option D is the best solution to eliminate the customer’s concern. References: Lifecycle hooks and Alibaba Cloud Auto Scaling.

Before data communication is set up, the security groups match the security group rules one by one to query whether to allow access requests. If the protocol type, port range, authorization type, and authorization object of two security group rules are the same, the following rules apply:

If the two rules have the same priority, the rule of the denial policy takes effect first, and the rule of the allowed policy does not take effect. This is because the security group rules follow the principle of minimum permission, which means that the most restrictive rule is applied when there is a conflict.

If the two rules have different priorities, the rule with a smaller priority number takes effect. This is because the security group rules follow the principle of priority, which means that the rule with a higher priority (lower number) is applied when there is a conflict. References: ECS Security Groups - Alibaba Fundamentals - Cloud Academy, Security group rules - Elastic Compute Service - Alibaba Cloud Documentation Center

 To execute a task at a specific time such as removing 1 ECS instance every night at 00:00, you need to perform two operations: create a scaling rule and create a scheduled task. A scaling rule is a set of instructions that defines how Auto Scaling scales computing resources in response to changes in business load. A scheduled task is a type of scaling task that can execute a specified scaling rule at a specified time. By creating a scaling rule that removes 1 ECS instance from the scaling group, and creating a scheduled task that executes this scaling rule every night at 00:00, you can achieve the desired result. You do not need to create a new scaling group, because you already have one scaling group created. You also do not need to create an event-triggered task, because this type of scaling task is triggered by events such as Cloud Monitor alarms or API calls, not by a specific time. References: 1, 2, and 3.