Multi-AZ deployment for high availability in AWS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the deployment type for high availability in AWS RDS.

AWS

rds_instance = aws_db_instance(
    identifier='mydb',
    multi_az=[1],
    engine='mysql',
    instance_class='db.t3.medium'
)

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

A'yes'

BFalse

CTrue

D'multi-az'

Attempts:

3 left

💡 Hint

Common Mistakes

Using string values instead of boolean.

Setting multi_az to False disables high availability.

Setting multi_az to True enables Multi-AZ deployment for high availability.

2fill in blank

medium

Complete the code to create an Auto Scaling group that spans multiple Availability Zones.

AWS

asg = aws_autoscaling_group(
    name='web-asg',
    availability_zones=[1],
    min_size=2,
    max_size=5
)

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

A['us-east-1a', 'us-east-1b']

B['us-east-1a']

C['us-east-1']

D['us-east-1a', 'us-east-1a']

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one AZ disables Multi-AZ benefits.

Repeating the same AZ twice does not increase availability.

Specifying multiple distinct Availability Zones ensures the Auto Scaling group spans them for high availability.

3fill in blank

hard

Fix the error in the subnet configuration to enable Multi-AZ deployment.

AWS

subnet_ids = [
    'subnet-12345',
    [1]
]

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

A'subnet-67890'

B'subnet-12345a'

C'subnet-12345'

D'subnet-12345b'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same subnet twice.

Using invalid subnet IDs.

For Multi-AZ, subnets must be in different Availability Zones. Using a different subnet ID like 'subnet-67890' ensures this.

4fill in blank

hard

Fill both blanks to configure an Elastic Load Balancer with listeners for HTTP and HTTPS across multiple AZs.

AWS

elb = aws_elb(
    name='my-elb',
    availability_zones=[1],
    listeners=[
        {'protocol': 'HTTP', 'load_balancer_port': 80, 'instance_port': 80},
        {'protocol': 'HTTPS', 'load_balancer_port': 443, 'instance_port': [2]
    ]
)

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

A['us-west-2a', 'us-west-2b']

B['us-west-2a']

C443

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one AZ disables Multi-AZ benefits.

Setting instance port to 443 for HTTPS listener without proper backend config.

Multiple AZs ensure high availability. HTTPS listener should forward to instance port 80 or 443 depending on setup; here 80 is common.

5fill in blank

hard

Fill all three blanks to define a Route 53 health check and failover routing policy for Multi-AZ high availability.

AWS

health_check = aws_route53_health_check(
    fqdn='example.com',
    port=[1],
    type='HTTP',
    resource_path='/',
    failure_threshold=3
)

record = aws_route53_record(
    zone_id='Z123456789',
    name='app.example.com',
    type='A',
    alias=[2],
    set_identifier='primary',
    failover=[3]
)

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

A80

B{'name': 'elb.amazonaws.com', 'zone_id': 'Z0987654321', 'evaluate_target_health': True}

CPRIMARY

D443

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong port for health check.

Incorrect alias format.

Failover value must be 'PRIMARY' or 'SECONDARY'.

Port 80 is standard for HTTP health checks. Alias points to ELB with health evaluation. Failover set to PRIMARY for main site.

Practice

1. What is the main benefit of using a Multi-AZ deployment in AWS?

easy

A. It increases availability by replicating resources across multiple zones.

B. It reduces the cost of running resources.

C. It speeds up the deployment process.

D. It automatically scales resources based on traffic.

Solution

1. Step 1: Understand Multi-AZ purpose

   Multi-AZ deployment copies resources to different zones to avoid downtime if one zone fails.

2. Step 2: Identify the main benefit

   This replication increases availability and fault tolerance, not cost reduction or speed.

3. Final Answer:

   It increases availability by replicating resources across multiple zones. -> Option A

4. Quick Check:

   Multi-AZ = High availability [OK]

Hint: Multi-AZ means copies in different zones for uptime [OK]

Common Mistakes:

• Confusing Multi-AZ with cost saving
• Thinking Multi-AZ speeds deployment
• Assuming Multi-AZ auto-scales resources

2. Which of the following is the correct way to enable Multi-AZ deployment in an AWS RDS instance configuration?

easy

A. "multi_az = false"

B. "enable_multi_az = yes"

C. "multi_az = true"

D. "multiAZ = enabled"

Solution

1. Step 1: Review AWS RDS Multi-AZ syntax

   The correct parameter to enable Multi-AZ is multi_az = true.

2. Step 2: Check other options for correctness

   Options A disables Multi-AZ, C and D use incorrect parameter names or values.

3. Final Answer:

   "multi_az = true" -> Option C

4. Quick Check:

   Enable Multi-AZ with multi_az = true [OK]

Hint: Look for exact parameter name and true value [OK]

Common Mistakes:

• Using false instead of true
• Wrong parameter names like enable_multi_az
• Incorrect value formats like yes or enabled

3. Given this AWS CLI command to create an RDS instance with Multi-AZ enabled:

aws rds create-db-instance --db-instance-identifier mydb --engine mysql --allocated-storage 20 --db-instance-class db.t3.micro --multi-az true

What will happen if the primary AZ fails?

medium

A. AWS will automatically failover to the standby instance in another AZ.

B. The database will stop working until manual recovery.

C. The database will scale up resources automatically.

D. The database will delete all data and restart.

Solution

1. Step 1: Understand Multi-AZ failover behavior

   Multi-AZ creates a standby in another zone that AWS switches to automatically if the primary fails.

2. Step 2: Analyze options

   AWS will automatically failover to the standby instance in another AZ. matches this automatic failover. Others describe stopping, scaling, or deleting which are incorrect.

3. Final Answer:

   AWS will automatically failover to the standby instance in another AZ. -> Option A

4. Quick Check:

   Multi-AZ = automatic failover [OK]

Hint: Multi-AZ means automatic failover on AZ failure [OK]

Common Mistakes:

• Thinking manual recovery is needed
• Confusing failover with scaling
• Assuming data loss on failover

4. You configured an RDS instance with multi_az = true but noticed no standby instance is created. What is the most likely cause?

medium

A. You selected a DB instance class that does not support Multi-AZ.

B. You used the wrong database engine.

C. You set allocated storage too low.

D. You forgot to enable automatic backups.

Solution

1. Step 1: Check Multi-AZ requirements

   Automatic backups must be enabled for Multi-AZ standby creation.

2. Step 2: Evaluate other options

   While some instance classes may not support Multi-AZ, the most common cause for no standby is backups not enabled. Storage size and engine choice usually don't prevent standby creation.

3. Final Answer:

   You forgot to enable automatic backups. -> Option D

4. Quick Check:

   Automatic backups required for Multi-AZ standby [OK]

Hint: Enable automatic backups to allow Multi-AZ standby creation [OK]

Common Mistakes:

• Assuming backups are optional for Multi-AZ
• Blaming storage size for standby absence
• Thinking engine type prevents standby

5. You want to design a highly available web application using AWS RDS with Multi-AZ and EC2 instances. Which architecture best ensures minimal downtime during an AZ failure?

hard

A. Deploy EC2 instances in a single AZ with RDS Multi-AZ enabled.

B. Deploy EC2 instances across multiple AZs and enable RDS Multi-AZ.

C. Deploy EC2 instances in multiple AZs but disable RDS Multi-AZ.

D. Deploy EC2 instances and RDS in a single AZ without Multi-AZ.

Solution

1. Step 1: Understand high availability for both compute and database

   To avoid downtime, both EC2 and RDS should be spread across AZs.

2. Step 2: Analyze options

   Deploy EC2 instances across multiple AZs and enable RDS Multi-AZ. deploys EC2 instances in multiple AZs and enables RDS Multi-AZ, ensuring failover for both layers.

3. Step 3: Reject other options

   Configurations with EC2 instances in a single AZ risk downtime if that AZ fails. Configurations with EC2 across multiple AZs but RDS Multi-AZ disabled risk database downtime.

4. Final Answer:

   Deploy EC2 instances across multiple AZs and enable RDS Multi-AZ. -> Option B

5. Quick Check:

   Multi-AZ + multi-AZ EC2 = minimal downtime [OK]

Hint: Spread both EC2 and RDS across AZs for full availability [OK]

Common Mistakes:

• Deploying EC2 in one AZ only
• Disabling RDS Multi-AZ
• Ignoring compute layer availability