ACP-Cloud1 Exam Dumps : ACP Cloud Computing Certification

The maximum number of connections to an RDS instance primarily depends on the memory size of the instance. Higher memory capacity allows for more simultaneous connections, as memory is a key resource in managing and maintaining connections. Alibaba Cloud RDS scales the connection limit based on the instance's memory allocation to ensure stable database performance.

 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.

When using Alibaba Cloud SLB to forward layer 7 (HTTP) service requests, SLB will replace the IP address in the HTTP header file to forward requests. Therefore, the source IP address that can be seen on the backend ECS instance is the IP address of SLB instead of the client’s real IP address. However, SLB also provides a feature called X-Forwarded-For (XFF) that can help you obtain the real IP address of the client. XFF is a standard HTTP header field that records the original IP address of the client and the proxy servers that the request passes through. You can enable XFF on the SLB console or by using the API, and then configure your backend ECS instance to parse the XFF header field and get the real IP address of the client. References: 1 - SLB overview - Alibaba Cloud Document Center - Layer 7 listeners - X-Forwarded-For