This PCSE practice question tests your understanding of configuring network security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO of the following are valid methods for sending traffic between VPC networks in Google Cloud? (Choose two.)
Firewall rules in each VPC
Why wrong: Incorrect: firewall rules filter, they do not route.
Subnet routes
Why wrong: Incorrect: subnet routes are internal to a VPC.
Cloud VPN (HA VPN gateway)
Correct: creates encrypted tunnels between VPCs.
Cloud NAT
Why wrong: Incorrect: Cloud NAT provides outbound internet, not VPC-to-VPC.
VPC Network Peering
Correct: enables internal IP connectivity between VPCs.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Cloud VPN (HA VPN gateway)
Cloud VPN (HA VPN gateway) is a valid method for sending traffic between VPC networks because it creates an encrypted tunnel over the public internet using IPsec (IKEv2) to connect two VPCs or an on-premises network to a VPC. It supports dynamic routing via BGP, allowing traffic to flow between VPCs when each VPC has a VPN gateway and the appropriate tunnel configurations.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Firewall rules in each VPC
Why it's wrong here
Incorrect: firewall rules filter, they do not route.
Subnet routes
Why it's wrong here
Incorrect: subnet routes are internal to a VPC.
Cloud VPN (HA VPN gateway)
Why this is correct
Correct: creates encrypted tunnels between VPCs.
Related concept
Read the scenario before looking for a memorised answer.
Cloud NAT
Why it's wrong here
Incorrect: Cloud NAT provides outbound internet, not VPC-to-VPC.
VPC Network Peering
Why this is correct
Correct: enables internal IP connectivity between VPCs.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates confuse Cloud NAT or firewall rules as a method for inter-VPC connectivity, when in fact they serve entirely different purposes (outbound NAT and access control, respectively) and cannot route traffic between separate VPC networks.
Detailed technical explanation
VPC Network Peering uses the Google Cloud private backbone to connect two VPCs with low latency and no bandwidth limits, leveraging RFC 1918 addresses without requiring VPN tunnels or public IPs. Under the hood, peering establishes a direct Layer 3 connection where routes are exchanged via the Google Cloud routing stack, but it does not support transitive peering—if VPC A is peered with VPC B and VPC B with VPC C, traffic from A to C must go through a VPN or another peering directly. A real-world scenario is connecting development and production VPCs in different projects while maintaining isolated management domains.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
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FAQ
Configuring network security — This question tests Configuring network security — Read the scenario before looking for a memorised answer..
The correct answer is: Cloud VPN (HA VPN gateway) — Cloud VPN (HA VPN gateway) is a valid method for sending traffic between VPC networks because it creates an encrypted tunnel over the public internet using IPsec (IKEv2) to connect two VPCs or an on-premises network to a VPC. It supports dynamic routing via BGP, allowing traffic to flow between VPCs when each VPC has a VPN gateway and the appropriate tunnel configurations.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This PCSE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCSE exam.
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