Multi-tier architecture patterns in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a multi-tier architecture pattern?

A multi-tier architecture pattern divides an application into layers or tiers, such as presentation, logic, and data. Each tier handles a specific role, making the system easier to manage and scale.

beginner

Name the common tiers in a three-tier architecture.

The common tiers are: 1) Presentation tier (user interface), 2) Application tier (business logic), 3) Data tier (database and storage).

intermediate

Why use multi-tier architecture in cloud applications?

It improves scalability, security, and maintenance by separating concerns. Each tier can be updated or scaled independently without affecting others.

intermediate

In AWS, which services can be used for the data tier in a multi-tier architecture?

AWS services like Amazon RDS, Amazon DynamoDB, and Amazon S3 are commonly used for the data tier to store structured and unstructured data.

intermediate

How does the application tier in AWS typically handle business logic?

The application tier can use AWS Elastic Beanstalk, AWS Lambda, or Amazon EC2 instances to run the business logic and process requests from the presentation tier.

Which tier in a multi-tier architecture handles user interaction?

A Application tier

B Network tier

C Data tier

D Presentation tier

The presentation tier is responsible for the user interface and interaction.

Which AWS service is best suited for storing relational data in the data tier?

A Amazon RDS

B Amazon S3

C AWS Lambda

D Amazon EC2

Amazon RDS is a managed relational database service ideal for structured data.

What is a key benefit of separating an application into multiple tiers?

A Easier maintenance and scalability

B Faster internet speed

C Lower electricity usage

D More complex code

Separating tiers allows independent updates and scaling, improving maintenance and scalability.

Which tier typically contains the business logic in a multi-tier architecture?

A Presentation tier

B Application tier

C Security tier

D Data tier

The application tier processes business rules and logic.

Which AWS service can be used to run code without managing servers in the application tier?

A Amazon EC2

B Amazon S3

C AWS Lambda

D Amazon RDS

AWS Lambda runs code in response to events without server management.

Explain the roles of each tier in a three-tier architecture pattern.

Think about how a website shows pages, processes actions, and stores information.

Describe how AWS services can be used to build each tier in a multi-tier architecture.

Consider which AWS services handle user access, code execution, and data storage.

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