ACP-Cloud1 Exam Dumps : ACP Cloud Computing Certification

The X-Forwarded-For field in HTTP header is used to identify the originating IP address of a client connecting to a web server through an HTTP proxy or a load balancer. When the “Obtain the Visitor’s Real IP Address” function is enabled in Alibaba Cloud SLB, the SLB instance adds the X-Forwarded-For field to the HTTP header of each request and forwards the request to the backend server. The backend server can then obtain the real IP address of the visitor from the X-Forwarded-For field1. The format of the X-Forwarded-For field is as follows:

X-Forwarded-For: client, proxy1, proxy2

where the value is a comma+space separated list of IP addresses, the left-most being the original client, and each successive proxy that passed the request adding the IP address where it received the request from. In this example, the request passed through proxy1, proxy2, and then the SLB instance (proxy3).2

References: Obtain client IP addresses - Server Load Balancer - Alibaba Cloud, X-Forwarded-For - MDN Web Docs

Alibaba Cloud Security Center is designed to enhance the security of ECS instances by providing proactive monitoring, vulnerability detection, and protection against threats such as brute-force attacks. Security Center includes features such as brute-force attack detection, which will alert you to and help mitigate potential threats to your ECS instance.

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The DNS service provider used by the domain name (such as abc.com) does not need to support intelligent resolution, because the CNAME address allocated to the domain name will point to an IP address that is intelligently managed by Alibaba Cloud CDN system. Therefore, option C is not a correct description of modifying domain name resolution. References: What is Alibaba Cloud CDN? - CDN - Alibaba Cloud Documentation Center and Alibaba Cloud CDN