This PCNE practice question tests your understanding of implementing network security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
A developer wants to SSH into a Compute Engine instance that has no public IP. Which service should they use?
Direct Peering.
Why wrong: Direct Peering is for on-premises to GCP, not instance SSH.
Cloud NAT.
Why wrong: Cloud NAT provides outbound internet, not inbound SSH.
Identity-Aware Proxy (IAP) TCP forwarding.
IAP allows SSH access without a public IP.
Cloud VPN.
Why wrong: Cloud VPN connects networks, not individual instance SSH.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Identity-Aware Proxy (IAP) TCP forwarding.
Identity-Aware Proxy (IAP) TCP forwarding allows secure, authenticated, and authorized SSH access to Compute Engine instances that have no public IP addresses. It works by establishing a tunnel through the IAP service, which proxies the SSH connection over HTTPS (port 443) to the instance's internal IP, eliminating the need for a public IP or bastion host.
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.
Common exam traps
Google Cloud often tests the misconception that Cloud NAT or Cloud VPN can provide inbound SSH access to private instances, but Cloud NAT is outbound-only and Cloud VPN requires a routable private IP and does not include IAM-based authentication, making IAP TCP forwarding the only correct choice for secure, authenticated SSH without a public IP.
Detailed technical explanation
IAP TCP forwarding uses the gcloud compute start-iap-tunnel command, which creates a local TCP listener that forwards traffic through an encrypted tunnel to the IAP service, which then proxies it to the instance's internal IP on port 22. The IAP service enforces Identity and Access Management (IAM) roles (e.g., roles/iap.tunnelResourceAccessor) and checks that the user has the necessary permissions before allowing the connection, providing a zero-trust access model. In real-world scenarios, this eliminates the need for bastion hosts or public IPs, reducing attack surface and simplifying compliance with security policies that prohibit public-facing management interfaces.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
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FAQ
Implementing network security — This question tests Implementing network security — Read the scenario before looking for a memorised answer..
The correct answer is: Identity-Aware Proxy (IAP) TCP forwarding. — Identity-Aware Proxy (IAP) TCP forwarding allows secure, authenticated, and authorized SSH access to Compute Engine instances that have no public IP addresses. It works by establishing a tunnel through the IAP service, which proxies the SSH connection over HTTPS (port 443) to the instance's internal IP, eliminating the need for a public IP or bastion host.
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 30, 2026
This PCNE 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 PCNE exam.
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