Custom VPC creation in GCP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the network mode as custom when creating a VPC in GCP.

GCP

resource "google_compute_network" "custom_vpc" {
  name                    = "custom-vpc"
  auto_create_subnetworks = [1]
}

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

Afalse

Bnull

C"custom"

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Setting auto_create_subnetworks to true creates an automatic VPC, not custom.

Using string values like "custom" instead of boolean false.

Setting auto_create_subnetworks to false creates a custom mode VPC where you manually define subnets.

2fill in blank

medium

Complete the code to define a subnet with the correct IP range in the custom VPC.

GCP

resource "google_compute_subnetwork" "custom_subnet" {
  name          = "custom-subnet"
  ip_cidr_range = "[1]"
  network       = google_compute_network.custom_vpc.id
  region        = "us-central1"
}

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

A10.0.0.0/16

B192.168.1.0/24

C172.16.0.0/12

D0.0.0.0/0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0.0.0.0/0 which is invalid for subnet IP range.

Using public IP ranges instead of private ones.

The subnet IP range must be a valid CIDR block within private IP ranges. 10.0.0.0/16 is a common private range used for subnets.

3fill in blank

hard

Fix the error in the subnet resource by selecting the correct region value.

GCP

resource "google_compute_subnetwork" "custom_subnet" {
  name          = "custom-subnet"
  ip_cidr_range = "10.0.1.0/24"
  network       = google_compute_network.custom_vpc.id
  region        = "[1]"
}

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

Aus-central1-a

Bus-west1-b

Cglobal

Dus-central1

Attempts:

3 left

💡 Hint

Common Mistakes

Using zone names like 'us-central1-a' instead of region names.

Using 'global' which is invalid for subnet region.

The region field for a subnet must be a region name, not a zone or global. us-central1 is a valid region.

4fill in blank

hard

Fill both blanks to create a firewall rule allowing SSH access to the custom VPC.

GCP

resource "google_compute_firewall" "allow_ssh" {
  name    = "allow-ssh"
  network = google_compute_network.custom_vpc.id

  allow {
    protocol = "[1]"
    ports    = ["[2]"]
  }

  direction = "INGRESS"
  source_ranges = ["0.0.0.0/0"]
}

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

Atcp

B22

Cudp

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using UDP protocol which SSH does not use.

Using port 80 which is for HTTP, not SSH.

SSH uses TCP protocol on port 22. The firewall rule must allow TCP on port 22 for SSH access.

5fill in blank

hard

Fill all three blanks to create a route in the custom VPC that directs traffic to the internet gateway.

GCP

resource "google_compute_route" "default_internet_route" {
  name       = "default-internet-route"
  network    = google_compute_network.custom_vpc.id
  dest_range = "[1]"
  next_hop_gateway = "[2]"
  priority   = [3]
}

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

A0.0.0.0/0

Bdefault-internet-gateway

C1000

Ddefault-gateway

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect next hop gateway names.

Setting priority too low or using invalid values.

The destination range 0.0.0.0/0 covers all IPs. The next hop gateway for internet access is default-internet-gateway. Priority is usually set to 1000 for custom routes.

Practice

1. What is the main advantage of creating a Custom VPC in Google Cloud Platform?

easy

A. You can define your own IP address ranges and subnets.

B. It automatically creates default firewall rules.

C. It provides free internet access without configuration.

D. It disables all network traffic by default.

Solution

1. Step 1: Understand Custom VPC purpose

   A Custom VPC allows you to design your network with your own IP ranges and subnets, unlike default VPCs which have preset ranges.

2. Step 2: Eliminate wrong options

   Custom VPC does not disable traffic, default firewall rules exist regardless, free internet requires configuration.

3. Final Answer:

   You can define your own IP address ranges and subnets. -> Option A

4. Quick Check:

   Custom VPC = Custom IP ranges [OK]

Hint: Custom VPC means you pick your IP ranges [OK]

Common Mistakes:

• Confusing default VPC with custom VPC
• Thinking firewall rules are auto-created
• Assuming internet access is automatic

2. Which gcloud command correctly creates a custom VPC named my-vpc with no automatic subnet creation?

easy

A. gcloud compute networks create my-vpc --subnet-mode=auto

B. gcloud compute networks create my-vpc --auto-create-subnetworks

C. gcloud compute networks create my-vpc --no-subnet-mode

D. gcloud compute networks create my-vpc --subnet-mode=custom

Solution

1. Step 1: Identify subnet mode for custom VPC

   Custom VPC requires the flag --subnet-mode=custom to avoid automatic subnet creation.

2. Step 2: Evaluate options

   --subnet-mode=auto creates automatic subnets. --auto-create-subnetworks uses invalid syntax. --no-subnet-mode does not exist.

3. Final Answer:

   gcloud compute networks create my-vpc --subnet-mode=custom -> Option D

4. Quick Check:

   Custom VPC uses --subnet-mode=custom [OK]

Hint: Use --subnet-mode=custom to create custom VPC [OK]

Common Mistakes:

• Using --subnet-mode=auto instead of custom
• Using invalid flags like --no-subnet-mode
• Assuming subnets are created automatically

3. Given this command:

gcloud compute networks subnets create subnet-1 --network=my-vpc --region=us-central1 --range=10.0.1.0/24

What is the CIDR range assigned to subnet-1?

medium

A. 10.0.0.0/16

B. 192.168.1.0/24

C. 10.0.1.0/24

D. 10.1.0.0/24

Solution

1. Step 1: Read the subnet creation command

   The command specifies --range=10.0.1.0/24 which sets the IP range for the subnet.

2. Step 2: Match the CIDR range

   10.0.1.0/24 matches the exact CIDR range given in the command.

3. Final Answer:

   10.0.1.0/24 -> Option C

4. Quick Check:

   Subnet range = 10.0.1.0/24 [OK]

Hint: Look for --range flag for subnet CIDR [OK]

Common Mistakes:

• Confusing VPC range with subnet range
• Picking wrong CIDR block from options
• Ignoring the --range parameter

4. You ran this command to create a subnet:

gcloud compute networks subnets create subnet-2 --network=my-vpc --region=us-east1 --range=10.0.1.0/24

But you get an error saying the IP range overlaps with an existing subnet. What is the likely cause?

medium

A. The subnet range 10.0.1.0/24 overlaps with another subnet in the same VPC.

B. The region us-east1 is invalid for subnet creation.

C. The network my-vpc does not exist.

D. The command is missing the --subnet-mode flag.

Solution

1. Step 1: Understand the error message

   The error about overlapping IP range means the subnet's CIDR block conflicts with an existing subnet in the same VPC.

2. Step 2: Check other options

   Region and network existence errors produce different messages; --subnet-mode is for network creation, not subnet.

3. Final Answer:

   The subnet range 10.0.1.0/24 overlaps with another subnet in the same VPC. -> Option A

4. Quick Check:

   Overlapping CIDR causes subnet creation error [OK]

Hint: Check subnet CIDR overlaps before creating [OK]

Common Mistakes:

• Assuming region is invalid without checking
• Confusing network creation flags with subnet flags
• Ignoring existing subnet CIDR ranges

5. You want to create a custom VPC named prod-vpc with two subnets:
- subnet-a in us-west1 with range 10.10.1.0/24
- subnet-b in us-east1 with range 10.10.2.0/24
Which sequence of gcloud commands correctly creates this setup?

hard

A. 1) gcloud compute networks create prod-vpc --subnet-mode=auto
2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.1.0/24
3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.2.0/24

B. 1) gcloud compute networks create prod-vpc --subnet-mode=custom
2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.1.0/24
3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.2.0/24

C. 1) gcloud compute networks create prod-vpc
2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.1.0/24
3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.2.0/24

D. 1) gcloud compute networks create prod-vpc --subnet-mode=custom
2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.2.0/24
3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.1.0/24

Solution

1. Step 1: Create the VPC with custom subnet mode

   The VPC must be created with --subnet-mode=custom to allow manual subnet creation.

2. Step 2: Create subnets with correct regions and CIDR ranges

   Subnets must be created with specified regions and matching CIDR ranges as per requirements.

3. Step 3: Verify order and correctness

   1) gcloud compute networks create prod-vpc --subnet-mode=custom 2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.1.0/24 3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.2.0/24 correctly creates the VPC first, then subnets with correct ranges and regions. 1) gcloud compute networks create prod-vpc --subnet-mode=auto 2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.1.0/24 3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.2.0/24 uses auto subnet mode which auto-creates subnets, conflicting with manual subnet creation. 1) gcloud compute networks create prod-vpc 2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.1.0/24 3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.2.0/24 misses subnet mode flag. 1) gcloud compute networks create prod-vpc --subnet-mode=custom 2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.2.0/24 3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.1.0/24 swaps CIDR ranges between subnets.

4. Final Answer:

   Correct sequence with custom subnet mode and matching subnet ranges -> Option B

5. Quick Check:

   Custom VPC + correct subnet ranges = 1) gcloud compute networks create prod-vpc --subnet-mode=custom 2) gcloud compute networks subnets create subnet-a --network=prod-vpc --region=us-west1 --range=10.10.1.0/24 3) gcloud compute networks subnets create subnet-b --network=prod-vpc --region=us-east1 --range=10.10.2.0/24 [OK]

Hint: Create VPC with --subnet-mode=custom before adding subnets [OK]

Common Mistakes:

• Using auto subnet mode when manual subnets needed
• Swapping subnet CIDR ranges by mistake
• Omitting --subnet-mode flag on VPC creation