Question

Difficulty: EasyVPC Network Security

An enterprise is building an internal human resources application on AWS. The application consists of a front-end server tier and a backend payroll database. The solutions architect needs to isolate the payroll database so that it has no direct route to or from the public internet, and it must only accept incoming traffic on port 54325432 from the front-end servers.

Which of the following configurations should the solutions architect implement to achieve this security posture? (Select TWO.)

  1. Associate the payroll database instances with private subnets that do not contain a route to an Internet Gateway in their route tables.Answer
  2. Add a rule to the payroll database security group that allows inbound traffic on port 54325432 from the security group of the front-end servers.Answer
  3. C
    Add an outbound rule to the database security group that explicitly denies all traffic to 0.0.0.0/00.0.0.0/0.
  4. D
    Configure a Network ACL on the database subnet that allows inbound traffic on port 54325432 but has no outbound rules, relying on the stateful response tracking of the subnet boundary.
  5. E
    Associate an AWS WAF Web ACL directly with the database subnet to inspect and filter incoming SQL traffic.

Answer

To secure the payroll database, place the database instances in private subnets that do not route to an Internet Gateway, and configure the database security group to allow inbound traffic on port 54325432 from the front-end server security group.
Placing the database in private subnets with no route to an Internet Gateway blocks all direct internet access. Configuring the database security group to reference the front-end server security group ensures that only the web tier can connect to the database on the database port, implementing secure least-privilege access.

Step-by-Step Solution

1
Isolate the network layer by deploying the database instances in private subnets.
Database instances have no direct route to the public internet.
This satisfies the requirement that the database must have no direct route to or from the public internet.
2
Configure the database security group with an inbound rule allowing port 54325432 traffic sourcing from the front-end security group.
Only front-end instances can establish connections to the database.
This restricts access to only the authorized application tier, adhering to security best practices.

Key Concept

VPC Network Security Isolation using Private Subnets and Stateful Security Group Rules
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