Alibaba Cloud Elastic Compute Service (ECS) instances in different Security Groups will definitely have no way to communicate with each other.
Answer(s): B
Alibaba Cloud Elastic Compute Service (ECS) instances in different security groups are isolated from each other by default, but they can communicate with each other if the security group rules allow it. A security group is a virtual firewall that controls the inbound and outbound traffic of ECS instances. You can configure security group rules to specify which IP addresses, protocols, and ports can access the ECS instances in a security group. You can also authorize other security groups to access the ECS instances in a security group, which enables cross-security group communication.
Manage ECS instances in security groups, Security FAQ, ECS Security Groups - Alibaba Fundamentals
Alibaba Cloud SLB can distribute user requests to backend ECS instances. These ECS instances must have the same specification (CPU, Memory)
Alibaba Cloud SLB can distribute user requests to backend ECS instances, but these ECS instances do not have to have the same specification (CPU, Memory). SLB virtualizes the added group of ECS instances in the same region into an application pool, and you can manage backend servers through either the default server group, a primary server group, or VServer groups. You can add ECS instances of different specifications to the same server group or VServer group according to your needs. SLB supports weighted round-robin (WRR) and weighted least connections (WLC) algorithms to balance the load among backend servers with different weights.
SLB overview - Alibaba CloudBackend server overview - Alibaba CloudWhat is Server Load Balancer and How It Works - Alibaba CloudServer Load Balancer - Alibaba CloudAlibaba Server Load Balancer (SLB) Course - Cloud Academy
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 clients real IP address.
Answer(s): A
When using Alibaba Cloud SLB to forward layer 7 (HTTP) service requests, SLB will replace the IPaddress 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.
1 - SLB overview - Alibaba Cloud Document Center - Layer 7 listeners - X-Forwarded-For
RDS provides whitelist access policies. You can set permitted IP addresses and IP network segments to effectively prevent hackers from attacking the server by port scanning.
RDS provides whitelist access policies. You can set permitted IP addresses and IP network segments to effectively prevent hackers from attacking the server by port scanning. A whitelist is a list of IP addresses or CIDR blocks that are allowed to access an RDS instance. By default, the whitelist is empty, which means that no IP address can access the RDS instance. You can add IP addresses or CIDR blocks to the whitelist to allow access from specific sources. You can also modify or delete the whitelist as needed. Whitelist access policies help improve the security of your RDS instance and protect your data from unauthorized access.
When creating an ECS instance in your Alibaba Cloud VPC, you must specify a VSwitch for that instance at the same time. Otherwise, you will not be able to create this ECS instance.
When creating an ECS instance in your Alibaba Cloud VPC, you must specify a VSwitch for that instance at the same time. Otherwise, you will not be able to create this ECS instance. This is true according to the Alibaba Cloud documentation on ECS1. A VSwitch is a basic network device of a VPC and is used to connect different cloud product instances deployed in a VPC2. A VSwitch defines a network segment within a VPC and allows you to specify the IP address range, network mask, and gateway for the network segment. When you create an ECS instance, you must select a VSwitch that belongs to the same zone as the ECS instance. If you do not specify a VSwitch, the ECS instance will not be able to communicate with other cloud product instances in the VPC or access the Internet.
1: Create an instance by using the provided wizard - Elastic Compute Service - Alibaba Cloud Documentation Center 2: What is a VSwitch? - Virtual Private Cloud - Alibaba Cloud Documentation Center 3: Create an instance by using the advanced wizard - Elastic Compute Service- Alibaba Cloud Documentation Center : [VPC FAQ - Virtual Private Cloud - Alibaba Cloud Documentation Center]
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