The correct action is to create egress firewall rules with target tags and allowed IP ranges. This approach works because egress rules in Google Cloud control outbound traffic from Compute Engine instances based on destination IP ranges, allowing you to specify the exact external IP ranges for updates while applying the rule only to instances tagged for that purpose. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of how to secure outbound access from internal-only instances without assigning public IPs—a common trap is confusing egress rules with ingress rules or assuming Cloud NAT is required for all outbound traffic. Remember, Cloud NAT provides outbound connectivity with source network address translation, but when you need to restrict outbound traffic to specific external IP ranges, egress firewall rules with target tags are the precise tool. Memory tip: think “Egress = Exit, Tags = Targets” to recall that egress rules control what leaves your VPC and tags define which instances are affected.
PCNE Implementing network security Practice Question
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 team has deployed Compute Engine instances with internal IPs only. They need to allow these instances to download updates from specific external IP ranges. Which action should they take?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create egress firewall rules with target tags and allowed IP ranges.
Egress firewall rules with target tags allow you to control outbound traffic from Compute Engine instances based on destination IP ranges. By specifying the allowed external IP ranges for updates and applying the rule to instances with a specific tag, you enable secure outbound access without exposing the instances to inbound traffic or requiring public IPs.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Create egress firewall rules with target tags and allowed IP ranges.
Why this is correct
Egress firewall rules can restrict outbound traffic to specific IP ranges.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure Cloud NAT and allow all traffic.
Why it's wrong here
Cloud NAT allows all outbound traffic, not just to specific IPs.
✗
Attach a public IP to each instance.
Why it's wrong here
Attaching public IPs is unnecessary and exposes instances to the internet.
✗
Use Private Google Access.
Why it's wrong here
Private Google Access only provides access to Google APIs, not arbitrary external IPs.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that Cloud NAT alone can restrict outbound traffic to specific destinations, but Cloud NAT only provides source NAT and does not filter traffic by destination; egress firewall rules are required for that control.
Detailed technical explanation
How to think about this question
Egress firewall rules in GCP are stateful, meaning return traffic is automatically allowed for established connections. When you create an egress rule with a target tag, you must specify the destination IP ranges (e.g., 203.0.113.0/24) and optionally a protocol/port (e.g., tcp:80,443) to match the update service. The rule is evaluated before the packet leaves the VPC, and if no matching egress rule allows the traffic, it is dropped by default.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Implementing network security — This question tests Implementing network security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create egress firewall rules with target tags and allowed IP ranges. — Egress firewall rules with target tags allow you to control outbound traffic from Compute Engine instances based on destination IP ranges. By specifying the allowed external IP ranges for updates and applying the rule to instances with a specific tag, you enable secure outbound access without exposing the instances to inbound traffic or requiring public IPs.
What should I do if I get this PCNE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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