Multi-tier architecture patterns in AWS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the compute layer in a multi-tier AWS architecture.

AWS

resource "aws_instance" "app_server" {
  instance_type = "[1]"
  ami           = "ami-0abcdef1234567890"
}

Drag options to blanks, or click blank then click option'

Ards.instance

Bs3.bucket

Clambda.function

Dt2.micro

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing storage or database services instead of compute instance type.

Using AWS Lambda or S3 where EC2 instance type is expected.

The compute layer in AWS multi-tier architecture is often an EC2 instance, specified by its instance type like t2.micro.

2fill in blank

medium

Complete the code to define the database tier in a multi-tier AWS architecture.

AWS

resource "aws_db_instance" "database" {
  engine         = "[1]"
  instance_class = "db.t3.micro"
  allocated_storage = 20
}

Drag options to blanks, or click blank then click option'

As3

Bdynamodb

Cmysql

Dec2

Attempts:

3 left

💡 Hint

Common Mistakes

Using NoSQL or storage services instead of a relational database engine.

Confusing compute services with database engines.

The database tier uses a database engine like mysql for relational databases in AWS RDS.

3fill in blank

hard

Fix the error in the code to correctly configure the web tier with a load balancer.

AWS

resource "aws_lb" "web_lb" {
  name               = "web-load-balancer"
  internal           = [1]
  load_balancer_type = "application"
  subnets            = ["subnet-12345", "subnet-67890"]
}

Drag options to blanks, or click blank then click option'

Afalse

B"true"

C"false"

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around boolean values causing syntax errors.

Setting internal to true when a public load balancer is needed.

The internal attribute expects a boolean value without quotes. Using false makes the load balancer internet-facing.

4fill in blank

hard

Fill both blanks to create a security group rule allowing HTTP traffic from anywhere.

AWS

resource "aws_security_group_rule" "allow_http" {
  type              = "ingress"
  from_port         = [1]
  to_port           = [2]
  protocol          = "tcp"
  cidr_blocks       = ["0.0.0.0/0"]
}

Drag options to blanks, or click blank then click option'

A80

B22

C443

D8080

Attempts:

3 left

💡 Hint

Common Mistakes

Using SSH port 22 or HTTPS port 443 instead of HTTP port 80.

Setting different values for from_port and to_port causing partial rules.

HTTP traffic uses port 80, so both from_port and to_port should be set to 80 to allow HTTP access.

5fill in blank

hard

Fill all three blanks to define an auto-scaling group with a launch configuration and desired capacity.

AWS

resource "aws_autoscaling_group" "asg" {
  launch_configuration = "[1]"
  min_size            = [2]
  desired_capacity    = [3]
  max_size            = 5
  vpc_zone_identifier = ["subnet-abcde", "subnet-fghij"]
}

Drag options to blanks, or click blank then click option'

Aapp_launch_config

B2

C3

Dapp_server

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect resource names for launch configuration.

Setting desired capacity less than minimum size.

The auto-scaling group uses a launch configuration named app_launch_config. The minimum size is 2, and the desired capacity is 3 instances.

Practice

1. What is the main purpose of using a multi-tier architecture in AWS?

easy

A. To combine all application components into a single server

B. To reduce the number of servers needed by merging databases and web servers

C. To separate an application into layers for better security and scalability

D. To allow direct internet access to all parts of the application

Solution

1. Step 1: Understand multi-tier architecture concept

   Multi-tier architecture divides an app into layers such as web, application, and database tiers.

2. Step 2: Identify benefits of layering

   This separation improves security by isolating layers and helps scale parts independently.

3. Final Answer:

   To separate an application into layers for better security and scalability -> Option C

4. Quick Check:

   Multi-tier = layers for security and scaling [OK]

Hint: Think layers for security and growth, not one big block [OK]

Common Mistakes:

• Thinking all parts should be on one server
• Assuming all components need internet access
• Confusing multi-tier with single-tier or monolithic

2. Which AWS subnet type is typically used to host internet-facing web servers in a multi-tier architecture?

easy

A. Public subnet

B. Isolated subnet

C. Private subnet

D. VPN subnet

Solution

1. Step 1: Recall subnet types in AWS

   Public subnets have a route to the internet gateway, allowing internet access.

2. Step 2: Match subnet to web servers

   Internet-facing web servers need public subnets to receive traffic from users.

3. Final Answer:

   Public subnet -> Option A

4. Quick Check:

   Internet-facing = public subnet [OK]

Hint: Public subnet means internet access for web servers [OK]

Common Mistakes:

• Choosing private subnet which blocks internet access
• Confusing isolated subnet with public
• Thinking VPN subnet is for public web servers

3. In a multi-tier AWS architecture, which tier is usually placed in a private subnet to protect sensitive data?

medium

A. Database tier

B. Application tier

C. Web tier

D. Load balancer tier

Solution

1. Step 1: Identify tiers and their security needs

   The database tier holds sensitive data and needs strong protection.

2. Step 2: Determine subnet placement

   Private subnets restrict internet access, ideal for databases to prevent direct exposure.

3. Final Answer:

   Database tier -> Option A

4. Quick Check:

   Database = private subnet for security [OK]

Hint: Sensitive data stays in private subnet (database) [OK]

Common Mistakes:

• Placing web tier in private subnet
• Assuming load balancer is in private subnet
• Confusing application tier with database tier

4. You deployed a multi-tier app but the application tier in the private subnet cannot connect to the database tier. What is the most likely cause?

medium

A. The load balancer is not configured

B. The web tier is in a public subnet

C. The application tier has a public IP address

D. The database security group does not allow inbound traffic from the application tier

Solution

1. Step 1: Analyze connectivity between application and database tiers

   Application tier must be allowed by database security group to connect on required ports.

2. Step 2: Check common misconfigurations

   If security group blocks inbound traffic, connection fails despite correct subnet placement.

3. Final Answer:

   The database security group does not allow inbound traffic from the application tier -> Option D

4. Quick Check:

   Security group rules control traffic between tiers [OK]

Hint: Check security group rules for inter-tier traffic [OK]

Common Mistakes:

• Blaming web tier subnet for app-db connection
• Assuming public IP needed for private subnet
• Ignoring security group inbound rules

5. You want to design a multi-tier AWS app with a public web tier, private application tier, and private database tier. Which setup best follows best practices?

hard

A. Place all tiers in public subnets with direct internet access for simplicity

B. Place web servers in public subnet with internet gateway; app and database servers in private subnets with NAT gateway for outbound internet

C. Place web and app tiers in private subnets; database in public subnet for easy access

D. Place web tier in private subnet; app and database tiers in public subnets

Solution

1. Step 1: Assign subnet types based on tier roles

   Web tier needs public subnet for user access; app and database tiers should be private for security.

2. Step 2: Provide outbound internet for private tiers

   Use NAT gateway so private tiers can access internet for updates without exposing them inbound.

3. Final Answer:

   Place web servers in public subnet with internet gateway; app and database servers in private subnets with NAT gateway for outbound internet -> Option B

4. Quick Check:

   Public web, private app/db, NAT for outbound [OK]

Hint: Public web, private app/db, NAT gateway outbound [OK]

Common Mistakes:

• Putting database in public subnet
• Giving private tiers direct internet access
• Mixing subnet roles incorrectly