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Alibaba Cloud ACA-Developer - ACA Developer Certification

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Total 95 questions

A developer creates a MySQL database service on a Linux ECS instance (ECS-A), and wants to access this database service from another instance (ECS-B) in the same VPC using the private IP address bound to the ECS instance, however, the connection can't be established. What could cause this? (Number of correct answers: 2)

A.

The security group for ECS-A does not have the default MySQL service port open.

B.

The built-in firewall on ECS-A has rules that prohibit external access to the MySQL service port.

C.

No Internet IP address is configured for ECS-A.

D.

The bind-address parameter set in the my.ini configuration file of the MySQL service is commented out.

During the process of backing up an RDS database, a developer found that the backup failed. What might cause this to happen?

A.

The database instance is not stopped

B.

DDL operations were performed during the backup

C.

DML operations were performed during the backup

D.

DCL operations were performed during the backup

Assume that a company uses ApsaraDB for PolarDB. The company commonly queries users based on their basic information, including: addresses, company names, and ID numbers. In this scenario, what is the best practice for creating a database index (or indexes)?

A.

Create a b-tree index on each column to be searched.

B.

Create a hash index on each column to be searched.

C.

Create a gin index for multiple fields.

D.

Create a gist index for multiple fields.

In PolarDB, if an UPDATE SQL statement encounters an issue, you need to check the execution plan to figure out the root cause. However, in the production environment, to avoid affecting the production data, what statement should you use to view the execution plan? (Number of correct answers: 2)

A.

explain SQL

B.

explain analyze SQL

C.

explain verbose SQL

D.

explain analyze verbose SQL

Which of the following options describes the basic concepts of Alibaba Cloud Tracing Analysis correctly? (Number of correct answers: 3)

A.

Alibaba Cloud Tracing Analysis model relies on OpenTracing

B.

In the OpenTracing standard, a call chain can be regarded as a directed acyclic graph (DAG) composed of multiple Spans. The relationship between spans is named References

C.

In the OpenTracing standard, each Span represents a named and timed non-continuous execution segment in the call chain

D.

In some cases, timing diagrams based on the timeline are used to show the call chain

Which of the following descriptions of Alibaba Cloud's SSL certificate service are correct? (Number of correct answers: 2)

A.

Alibaba Cloud SSL Certificate Service supports the purchase of three types of certificates: DV certificates, OV certificates, and EV certificates.

B.

EV certificates are suitable for large enterprises, financial institutions, etc.

C.

OV certificates are suitable for personal websites.

D.

DV level certificates are suitable for government organizations, enterprises, educational institutions, etc.

Which of the following operations can be performed through Log Service sAPI? (Number of correct answers: 3)

A.

Collect logs based on Logtail configuration and Logtail machine group information

B.

Create a Logstore, write and read logs to the Logstore

C.

Access control for different users

D.

Deliver logs to OSS for storage and analysis

When a developer calls the Alibaba Cloud SDK to access Elastic Compute Service (ECS), the following error is returned; RealNameAuthenticationError What is the possible cause?

A.

The ECS instance name violates the ECS service's naming conventions.

B.

The ECS instance name conflicts with other instance names.

C.

The user's Alibaba Cloud account has not passed real name authentication

D.

The API callers account and password are not authorized for ECS access.

Which of the following statements are correct, with regard to Alibaba Cloud Log Service? (Number of correct answers: 3)

A.

As an agent for collecting logs, Logtail can collect logs from existing system log files in a non-intrusive manner

B.

The Log Service frontend service adopts an LVS + NGINX architecture

C.

The Logstore backend service is deployed on a single machine to complete the real-time persistence, indexing, query and delivery of Logstore data to MaxCompute

D.

Each log written to the Log Service backend will be saved in triplicate (across three separate physical servers)

Which of the following statements about migrating data into and out of Object Storage Service (OSS) are correct? (Number of correct answers: 3)

A.

You can migrate data between OSS buckets in any of the following conditions: Buckets are located within the same region, buckets are located across regions and buckets belong to different Alibaba Cloud accounts.

B.

A migration job occupies the network resources of the source and the destination. To ensure business continuity, we recommend that you specify a rate limit for a migration Job or run the migration job during an off-peak period.

C.

You cannot migrate data between OSS buckets if the data at the source is stored in a bucket of the Archive type.

D.

Online migration supports both migrating buckets at a time, and migrating all the data under an Alibaba Cloud account at a single time.