A company website contains a web tier and a database tier on AWS. The web tier consists of Amazon EC2 instances that run in an Auto Scaling group across two Availability Zones. The database tier runs on an Amazon ROS for MySQL Multi-AZ DB instance. The database subnet network ACLs are restricted to only the web subnets that need access to the database. The web subnets use the default network ACL with the default rules.
The company's operations team has added a third subnet to the Auto Scaling group configuration. After an Auto Scaling event occurs, some users report that they intermittently receive an error message. The error message states that the server cannot connect to the database. The operations team has confirmed that the route tables are correct and that the required ports are open on all security groups.
Which combination of actions should a SysOps administrator take so that the web servers can communicate with the DB instance? (Select TWO.)