Your team has set up a VPC with multiple subnets. There is a webserver hosted in one subnet and a database server hosted in another subnet. During the initial test, the webserver could not establish communication with the database server. Which of the following would you need to check for this?

Answer options:

A.Ensure that the Internet gateway is attached to the VPC.B.Ensure that the route tables are modified so that communication is possible across subnets.
C.Ensure the security group for the database server is allowing the required inbound communication.
D.Ensure a public IP is assigned to the database server.

Correct Answer: C
The AWS Documentation mentions the following.
A security group acts as a virtual firewall that controls the traffic for one or more instances. When you launch an instance, you associate one or more security groups with the instance. You add rules to each security group that allows traffic to or from its associated instances. You can modify the rules for a security group at any time; the new rules are automatically applied to all instances associated with the security group. When we decide whether to allow traffic to reach an instance, we evaluate all the rules from all the security groups associated with the instance.
Option A is incorrect since this is an internal communication problem.
Option B is incorrect because the Route table defines the traffic that goes in and out of the subnet, cannot manage the traffic between servers just like Security groups.
Option D is incorrect because the communication with the database needs to be done via the Private IP for security concerns.
For more information on security groups, please visit the below URL-
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-network-security.html