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Custom VPC creation in GCP - Cheat Sheet & Quick Revision

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beginner
What is a Custom VPC in Google Cloud Platform?
A Custom VPC is a Virtual Private Cloud network where you manually create and control subnets, IP ranges, and routing. It gives you full control over your network layout.
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beginner
Why would you choose a Custom VPC over an Auto mode VPC?
You choose a Custom VPC to control subnet IP ranges, regions, and routing. It helps avoid IP conflicts and tailor the network to your needs.
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beginner
What is a subnet in a Custom VPC?
A subnet is a range of IP addresses in a specific region inside your VPC. It helps organize and isolate resources by location.
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intermediate
How do firewall rules relate to a Custom VPC?
Firewall rules control which traffic is allowed in and out of your VPC. They protect your resources by allowing only trusted connections.
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intermediate
What is the purpose of routing in a Custom VPC?
Routing directs network traffic between subnets, the internet, and other networks. It ensures data reaches the right destination.
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What must you define when creating a Custom VPC in GCP?
ASubnets with IP ranges and regions
BOnly the VPC name
CFirewall rules automatically
DDefault internet gateway
Which of these is NOT a benefit of using a Custom VPC?
AFull control over IP address ranges
BCustom routing rules
CAutomatic subnet creation in all regions
DBetter network isolation
What does a subnet represent in a Custom VPC?
AA firewall rule
BA group of IP addresses in a region
CA virtual machine
DA storage bucket
How do firewall rules affect a Custom VPC?
AThey manage billing
BThey create subnets automatically
CThey assign IP addresses
DThey control allowed network traffic
What is the role of routing in a Custom VPC?
ADirect traffic between subnets and networks
BCreate firewall rules
CAssign IP addresses to VMs
DMonitor network usage
Explain the key steps to create a Custom VPC in Google Cloud Platform.
Think about how you organize your home network with rooms and rules.
You got /4 concepts.
    Describe why controlling IP ranges and subnets is important in a Custom VPC.
    Imagine assigning house addresses carefully to avoid confusion.
    You got /4 concepts.

      Practice

      (1/5)
      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