AWS Certified Database - Specialty

The error message 'could not connect to server: Connection times out' commonly indicates an issue with network connectivity or firewalls. In the context of AWS, security groups act as virtual firewalls to control inbound and outbound traffic to instances. Since the application servers cannot connect to the database, it is likely that the security group associated with the DB instance does not have a rule allowing inbound connections on the MySQL default port (3306) from the application servers. Ensuring the correct security group rules are in place would resolve this connectivity issue.

To prevent accidental data loss of an Amazon RDS DB instance in an AWS CloudFormation stack, certain settings need to be configured. Setting DeletionProtection to True ensures that the RDS instance cannot be deleted accidentally. Setting DeleteAutomatedBackups to False prevents the deletion of automated backups, thus aiding in data recovery in case of accidental deletion. Setting DeletionPolicy to Retain ensures that the resources are retained even if the CloudFormation stack is deleted, rather than being deleted themselves. These measures collectively help in safeguarding against accidental data loss.

The 5-minute connection outage is most likely caused by the client-side application caching the DNS data with a time-to-live (TTL) set too high. After a failover, the underlying IP address of a DB instance can change. If the application continues to use a cached DNS entry with the old IP address, it will fail to connect to the new instance. Setting a shorter TTL for the DNS cache would ensure that the client application updates its DNS information quickly after a failover.

The Data Analysts are unable to connect to the Aurora DB cluster likely because the connection requires SSL/TLS and they have not configured their connections to use the SSL certificate. To connect using SSL/TLS, the Analysts need to download the root certificate provided by AWS and include it in their connection string. This ensures that the connection is secure, as required by the Database Specialist's settings. Restarting the DB cluster, modifying firewalls, or adding IP address mappings wouldn't address this SSL requirement directly.

To reduce the overall cost, the Database Specialist should create a new attribute in each table to track the expiration time and enable time to live (TTL) on each table. TTL automatically deletes expired items from the table without requiring manual intervention, effectively managing storage costs by ensuring that only necessary data is retained. Unlike complex solutions involving AWS Glue transformations or data pipelines, TTL is a native feature of DynamoDB designed specifically for this purpose and does not incur additional costs.