VPC peering in GCP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is VPC peering in Google Cloud Platform?

VPC peering is a way to connect two Virtual Private Cloud (VPC) networks so they can communicate privately using internal IP addresses, without going through the public internet.

beginner

Can two VPC networks in different projects be peered in GCP?

Yes, VPC peering can connect VPC networks across different projects as long as they are in the same or different organizations and meet peering requirements.

intermediate

What is a key limitation of VPC peering regarding transitive peering?

VPC peering does not support transitive peering. This means if VPC A is peered with VPC B, and VPC B is peered with VPC C, VPC A cannot communicate directly with VPC C through VPC B.

beginner

How does VPC peering affect network latency and security?

VPC peering provides low latency and secure communication because traffic stays within Google's private network and does not traverse the public internet.

beginner

What must you ensure about IP address ranges before creating a VPC peering connection?

The IP address ranges of the two VPC networks must not overlap to avoid routing conflicts and ensure proper communication.

What does VPC peering allow between two VPC networks?

A Public internet access

B Shared billing accounts

C Automatic VPN setup

D Private communication using internal IPs

VPC peering enables private communication between VPCs using internal IP addresses without using the public internet.

Can VPC peering connect VPCs with overlapping IP ranges?

A Yes, always

B No, IP ranges must not overlap

C Only if in the same project

D Only with VPN

VPC peering requires that the IP address ranges of the two VPCs do not overlap to avoid routing issues.

Which of the following is NOT true about VPC peering?

A It supports transitive peering

B It keeps traffic within Google's network

C It connects VPCs privately

D It can connect VPCs across projects

VPC peering does NOT support transitive peering; direct peering is required between each pair of VPCs.

What is a benefit of VPC peering over using the public internet?

A Increased security and lower latency

B Higher latency

C Requires public IPs

D No need for firewall rules

VPC peering keeps traffic private within Google's network, improving security and reducing latency.

Which Google Cloud service is used to create VPC peering?

A Cloud VPN

B Cloud Router

C VPC Network Peering

D Cloud Interconnect

VPC Network Peering is the service used to create peering connections between VPCs.

Explain what VPC peering is and why it is useful in Google Cloud.

Think about how two separate networks can talk safely and quickly.

Describe the main limitations and requirements you must consider before setting up VPC peering.

Focus on what can block or restrict peering connections.

Practice

1.

What is the main purpose of VPC peering in Google Cloud?

easy

A. To create a firewall rule between two networks

B. To connect two private networks securely without using the internet

C. To provide public internet access to virtual machines

D. To enable automatic backups of virtual machines

Solution

1. Step 1: Understand VPC peering concept

   VPC peering connects two private networks directly, avoiding the public internet.

2. Step 2: Compare options with concept

   Only To connect two private networks securely without using the internet describes secure private network connection without internet.

3. Final Answer:

   To connect two private networks securely without using the internet -> Option B

4. Quick Check:

   VPC peering = secure private network connection [OK]

Hint: VPC peering = private network connection, no internet needed [OK]

Common Mistakes:

• Confusing VPC peering with firewall rules
• Thinking VPC peering provides internet access
• Assuming VPC peering is for backups

2.

Which of the following is the correct command to create a VPC peering connection from net-a to net-b in Google Cloud CLI?

gcloud compute networks peerings create PEERING_NAME --network=NETWORK --peer-network=PEER_NETWORK

easy

A. gcloud compute networks peerings create peer-ab --network=net-a --peer-network=net-b

B. gcloud compute networks peerings create net-a --network=peer-ab --peer-network=net-b

C. gcloud compute networks peerings create net-b --network=net-a --peer-network=net-b

D. gcloud compute networks peerings create peer-ab --peer-network=net-a --network=net-b

Solution

1. Step 1: Identify correct command syntax

   The command requires a peering name, the local network, and the peer network.

2. Step 2: Match parameters to networks

   gcloud compute networks peerings create peer-ab --network=net-a --peer-network=net-b correctly uses a peering name and assigns net-a as local network and net-b as peer network.

3. Final Answer:

   gcloud compute networks peerings create peer-ab --network=net-a --peer-network=net-b -> Option A

4. Quick Check:

   Correct CLI syntax = gcloud compute networks peerings create peer-ab --network=net-a --peer-network=net-b [OK]

Hint: Peering name first, then --network local, --peer-network remote [OK]

Common Mistakes:

• Swapping --network and --peer-network values
• Using network names as peering name
• Omitting required flags

3.

Given two VPC networks net-a and net-b peered together, which of the following statements about routing is true?

1. Each network must create routes to the other's IP ranges.
2. Routes are automatically shared by default.
3. Peering allows communication only if firewall rules permit.
4. Peering replaces the need for VPN connections.

medium

A. Only statement 2 and 3 are true

B. Only statement 1 and 3 are true

C. Only statement 1 and 2 are true

D. Only statement 3 and 4 are true

Solution

1. Step 1: Analyze routing and firewall requirements

   VPC peering automatically shares subnet routes by default. Firewall rules still control traffic.

2. Step 2: Evaluate statements

   Statement 1 is false (no manual route creation needed). Statements 2 and 3 are true. Statement 4 is not accurate (peering and VPN serve different purposes).

3. Final Answer:

   Only statement 2 and 3 are true -> Option A

4. Quick Check:

   Routes auto + firewall needed [OK]

Hint: Routes automatically shared; firewall rules still apply [OK]

Common Mistakes:

• Thinking routes must be manually created
• Ignoring firewall rules in peering
• Thinking peering always replaces VPN

4.

You created a VPC peering between net-a and net-b, but instances in net-a cannot reach instances in net-b. What is the most likely cause?

medium

A. The peering connection was created only on net-a side

B. The peering connection was created with the wrong peering name

C. The VPC networks have overlapping IP ranges

D. Firewall rules in net-b block incoming traffic from net-a

Solution

1. Step 1: Check common connectivity issues in VPC peering

   Firewall rules must allow traffic between peered networks; blocking rules prevent communication.

2. Step 2: Evaluate other options

   Wrong peering name or one-sided peering would prevent peering creation. Overlapping IP ranges prevent peering setup itself.

3. Final Answer:

   Firewall rules in net-b block incoming traffic from net-a -> Option D

4. Quick Check:

   Firewall blocking = connectivity failure [OK]

Hint: Check firewall rules first when peering connectivity fails [OK]

Common Mistakes:

• Ignoring firewall rules as cause
• Assuming peering auto-fixes IP conflicts
• Thinking peering is one-sided

5.

You have two VPC networks, net-a with CIDR 10.0.0.0/16 and net-b with CIDR 10.0.0.0/16. You want to peer them to share resources privately. What is the best approach?

hard

A. Create VPC peering directly between net-a and net-b despite overlapping CIDRs

B. Use VPN instead of VPC peering to connect the networks

C. Change one network's CIDR to a non-overlapping range before peering

D. Use shared VPC instead of peering for overlapping CIDRs

Solution

1. Step 1: Understand CIDR overlap restrictions in VPC peering

   VPC peering requires non-overlapping IP ranges to route traffic correctly.

2. Step 2: Choose solution for overlapping CIDRs

   Changing one network's CIDR to a non-overlapping range allows peering. VPN or shared VPC are alternatives but not direct peering solutions.

3. Final Answer:

   Change one network's CIDR to a non-overlapping range before peering -> Option C

4. Quick Check:

   Non-overlapping CIDRs required for peering [OK]

Hint: Peering needs unique IP ranges; change CIDR if overlapping [OK]

Common Mistakes:

• Trying to peer overlapping CIDRs directly
• Confusing VPN with peering
• Ignoring shared VPC as different concept