Elastic IP addresses in AWS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to allocate a new Elastic IP address using AWS CLI.

AWS

aws ec2 allocate-address --domain [1]

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

Aclassic

Bvpc

Cinternet

Dprivate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'classic' domain when your account uses VPC only.

Using invalid domain names like 'internet' or 'private'.

The vpc domain is used to allocate Elastic IPs for VPCs, which is the modern and common setup.

2fill in blank

medium

Complete the code to associate an Elastic IP address with an instance using AWS CLI.

AWS

aws ec2 associate-address --instance-id [1] --allocation-id eipalloc-12345678

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

Aeipalloc-87654321

Bsg-1234abcd

Csubnet-1234abcd

Di-0a1b2c3d4e5f6g7h8

Attempts:

3 left

💡 Hint

Common Mistakes

Using allocation ID instead of instance ID for --instance-id.

Using subnet or security group IDs instead of instance ID.

The instance-id requires the EC2 instance identifier, which starts with 'i-'.

3fill in blank

hard

Fix the error in the command to release an Elastic IP address.

AWS

aws ec2 release-address --allocation-id [1]

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

Aeipalloc-12345678

Beip-12345678

Ci-12345678

Dsubnet-12345678

Attempts:

3 left

💡 Hint

Common Mistakes

Using public IP (eip-) instead of allocation ID (eipalloc-).

Using instance or subnet IDs instead of allocation ID.

The allocation-id for releasing an Elastic IP starts with 'eipalloc-'.

4fill in blank

hard

Fill both blanks to create a tag for an Elastic IP address using AWS CLI.

AWS

aws ec2 create-tags --resources [1] --tags Key=[2],Value=Production

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

Aeipalloc-1a2b3c4d

Bi-1a2b3c4d

CName

DEnvironment

Attempts:

3 left

💡 Hint

Common Mistakes

Using instance ID instead of allocation ID for resources.

Using invalid tag keys.

You tag the Elastic IP using its allocation ID and a key like 'Name' to identify it.

5fill in blank

hard

Fill all three blanks to describe the correct AWS CLI command to disassociate an Elastic IP address.

AWS

aws ec2 disassociate-address --[1] [2] --region [3]

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

Aassociation-id

Beipassoc-1234abcd

Cus-east-1

Dallocation-id

Attempts:

3 left

💡 Hint

Common Mistakes

Using allocation-id instead of association-id for disassociation.

Omitting the region parameter.

To disassociate an Elastic IP, you use the association-id with its value and specify the region.

Practice

1. What is the main purpose of an Elastic IP address in AWS?

easy

A. To provide a fixed public IP address that can be reassigned to different instances

B. To increase the storage capacity of an EC2 instance

C. To encrypt data in transit between AWS services

D. To automatically scale the number of EC2 instances

Solution

1. Step 1: Understand Elastic IP purpose

   An Elastic IP is a static public IP address designed to be associated with AWS resources like EC2 instances.

2. Step 2: Identify its main use

   It allows you to keep the same public IP even if you stop and start or replace the instance, ensuring consistent reachability.

3. Final Answer:

   To provide a fixed public IP address that can be reassigned to different instances -> Option A

4. Quick Check:

   Elastic IP = Fixed public IP for instances [OK]

Hint: Elastic IP means fixed public IP for your server [OK]

Common Mistakes:

• Confusing Elastic IP with storage or encryption
• Thinking Elastic IP auto-scales instances
• Assuming Elastic IP changes on instance restart

2. Which AWS CLI command correctly allocates a new Elastic IP address?

easy

A. aws ec2 create-elastic-ip

B. aws ec2 assign-elastic-ip

C. aws ec2 new-ip-address

D. aws ec2 allocate-address

Solution

1. Step 1: Recall AWS CLI syntax for Elastic IP allocation

   The correct command to allocate a new Elastic IP is 'aws ec2 allocate-address'.

2. Step 2: Verify other options

   Other options are invalid AWS CLI commands and will cause errors.

3. Final Answer:

   aws ec2 allocate-address -> Option D

4. Quick Check:

   Allocate Elastic IP = aws ec2 allocate-address [OK]

Hint: Allocate Elastic IP with 'allocate-address' command [OK]

Common Mistakes:

• Using non-existent commands like create-elastic-ip
• Confusing allocation with assignment commands
• Misspelling the command name

3. Consider this AWS CLI output after associating an Elastic IP to an instance:

{
  "AssociationId": "eipassoc-12345678",
  "PublicIp": "203.0.113.25",
  "InstanceId": "i-0abcd1234efgh5678"
}

What does this output indicate?

medium

A. The Elastic IP 203.0.113.25 is now linked to the instance i-0abcd1234efgh5678

B. The instance i-0abcd1234efgh5678 has been terminated

C. The Elastic IP has been released and is no longer usable

D. The instance has no public IP assigned

Solution

1. Step 1: Analyze the output fields

   The output shows an AssociationId, a PublicIp, and an InstanceId, indicating a link between the IP and instance.

2. Step 2: Interpret the meaning

   This means the Elastic IP 203.0.113.25 is assigned to the instance i-0abcd1234efgh5678.

3. Final Answer:

   The Elastic IP 203.0.113.25 is now linked to the instance i-0abcd1234efgh5678 -> Option A

4. Quick Check:

   AssociationId means IP linked to instance [OK]

Hint: AssociationId means IP linked to instance [OK]

Common Mistakes:

• Thinking the instance is terminated
• Assuming the IP is released
• Ignoring the AssociationId meaning

4. You tried to associate an Elastic IP to an instance but got an error: "AddressLimitExceeded". What is the likely cause?

medium

A. The instance does not have an internet gateway attached

B. You have reached the maximum number of Elastic IPs allowed in your AWS account

C. The Elastic IP is not in the same region as the instance

D. The instance is already terminated

Solution

1. Step 1: Understand the error message

   "AddressLimitExceeded" means you have hit the limit of Elastic IPs you can allocate in your AWS account.

2. Step 2: Check other options

   Instance termination or region mismatch cause different errors; internet gateway absence affects connectivity but not this error.

3. Final Answer:

   You have reached the maximum number of Elastic IPs allowed in your AWS account -> Option B

4. Quick Check:

   AddressLimitExceeded = Max Elastic IPs reached [OK]

Hint: AddressLimitExceeded means max Elastic IPs reached [OK]

Common Mistakes:

• Confusing region mismatch with limit error
• Assuming instance termination causes this error
• Thinking internet gateway absence triggers this error

5. You have an Elastic IP associated with an EC2 instance. You stop and start the instance. What happens to the Elastic IP and the instance's public IP?

hard

A. The Elastic IP remains but the instance loses its public IP until reassigned

B. The Elastic IP is released automatically and the instance gets a new public IP

C. The Elastic IP remains associated and the instance keeps the same public IP

D. The Elastic IP dissociates and you must manually re-associate it

Solution

1. Step 1: Recall Elastic IP behavior on instance stop/start

   Elastic IPs remain allocated and associated with the instance even if it is stopped and started.

2. Step 2: Understand public IP behavior

   Without Elastic IP, the public IP changes on stop/start, but with Elastic IP, the public IP stays the same.

3. Final Answer:

   The Elastic IP remains associated and the instance keeps the same public IP -> Option C

4. Quick Check:

   Elastic IP keeps public IP fixed on stop/start [OK]

Hint: Elastic IP keeps public IP fixed after stop/start [OK]

Common Mistakes:

• Thinking Elastic IP is released on stop/start
• Assuming public IP changes despite Elastic IP
• Believing manual reassociation is needed