Alibaba Cloud ACA-Cloud1 Practice Test Questions Answers

ApsaraDB RDS for MySQL is a cloud-based relational database service that provides secure, cost-effective, and scalable database solutions for various applications. RDS for MySQL supports creating read-only instances that are synchronized with the primary instance in real time. Read-only instances can handle read requests from applications and reduce the read pressure on the primary instance. This can improve the performance and availability of the database system. Read-only instances can also be used for scenarios such as report analysis, data backup, and disaster recovery.

References:

Overview of read-only ApsaraDB RDS for MySQL instances

ACA Cloud Computing Certification Exam Preparation Course

Alibaba Cloud Computing Exam Question 2022

According to the Alibaba Cloud Academy, Alibaba Cloud OSS is a cloud storage service that features massive capacity, outstanding security, low cost, and high reliability. To control the access to the files stored on OSS, OSS provides multiple access permissions for each bucket. These bucket permissions are:

Public-read-write: Anyone, including anonymous users, can perform read and write operations on the objects in the bucket. The owner of the bucket is charged for the requests and traffic generated by these operations. This permission poses a high security risk and is not recommended.

Public-read: Only the owner of the bucket and authorized RAM users can perform write operations on the objects in the bucket. Anyone, including anonymous users, can perform read operations on the objects in the bucket. The owner of the bucket is charged for the requests and traffic generated by these operations.

Private: Only the owner of the bucket and authorized RAM users can perform read and write operations on the objects in the bucket. Other users, including anonymous users, are denied access to the objects in the bucket unless they have been granted temporary access permissions by the bucket owner or authorized RAM users.

Therefore, the options B, C, and D are the correct answers that describe the bucket permissions in OSS. References: OSS Security - Alibaba Object Storage Service Course - Cloud Academy, OSS Concepts - Alibaba Cloud Documentation Center

Alibaba Cloud OSS service provides different methods for file uploading, such as simple upload, multipart upload, append upload, and resumable upload1. However, not all of these methods support resuming from break point, which is a feature that allows you to resume an interrupted upload from where it left off. The only method that supports resuming from break point is resumable upload, which is based on multipart upload and uses a checkpoint file to record the upload progress2. The other methods do not support resuming from break point, and will either overwrite or append to the existing object if the upload is interrupted and retried.

References: 1: Alibaba Cloud Academy, “OSS Upload Methods”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-2-oss-upload-methods  2: Alibaba Cloud, “Resumable upload”, https://www.alibabacloud.com/help/doc-detail/31991.htm

SQL injection is a common application layer attack that targets the database of a web application. SQL injection exploits a security vulnerability in the application’s software, such as incorrect filtering of user input, that allows an attacker to send malicious SQL statements to the database. These statements can then be executed to steal, modify, or delete data, or even execute commands on the server1. SQL injection can also bypass authentication and authorization mechanisms, and sometimes even impersonate or damage the underlying system2. SQL injection is one of the most common and dangerous web attacks, and it can cause serious damage to the confidentiality, integrity, and availability of web applications3. References: 1: SQL Injection - OWASP2: SQL Injection - Web Application Firewall - Alibaba Cloud Documentation Center3: Web Application Firewall:What is WAF? - Alibaba Cloud.

 Prepaid is a charging mode that allows you to pay in advance for a certain amount of resources for a specified period of time. It is also known as subscription or reserved instance. Prepaid is more suitable for scenarios with relatively fixed traffic, such as an online ticket booking service, because it offers lower prices and more stable performance than pay-as-you-go. Pay-as-you-go is a charging mode that allows you to pay only for the resources you actually use on an hourly basis. It is more suitable for scenarios with unpredictable or fluctuating traffic, such as a news website or a social media platform. Paypal-pay and bitcoin-pay are not valid charging modes for Alibaba Cloud Computing products.

References: 1: Alibaba Cloud Academy, “Charging Modes”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-1-charging-modes