- A
Set a VPC connector and allow only internal traffic.
Why wrong: VPC connector enables private access but does not authenticate callers.
- B
Use Cloud Endpoints with API keys and IAM.
Cloud Endpoints provides robust authentication and authorization for HTTP triggers.
- C
Rely on the Cloud Functions URL being unguessable.
Why wrong: URL obscurity is not a security control; URLs can be exposed through logs or leaks.
- D
Use Firebase Authentication.
Why wrong: Firebase Authentication is for end-user identity, not for service-to-service calls.
Question 860 of 1,000
mediumMultiple ChoiceObjective-mapped
Securing HTTP-Triggered Cloud Functions
This PCSE practice question tests your understanding of pcse exam topics. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 company uses Cloud Functions and wants to ensure that only authorized services can invoke them. The functions are triggered via HTTP. What is the best way to achieve this?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Quick Answer
The answer is to use Cloud Endpoints with API keys and IAM. This combination is correct because Cloud Endpoints acts as a dedicated API gateway that authenticates incoming HTTP requests via API keys, then authorizes them against IAM policies, providing fine-grained access control for service-to-service invocation. On the Google Professional Cloud Security Engineer exam, this scenario tests your understanding of how to secure HTTP-triggered Cloud Functions beyond simple URL obscurity, often appearing as a trap where candidates confuse internal network controls (like VPC connectors) or mobile-specific solutions (like Firebase Authentication) with general service authorization. A common mistake is assuming that keeping the function URL secret is sufficient, but the exam emphasizes that URLs can be guessed or leaked, making IAM-backed gateways essential. Remember the mnemonic: "Keys at the Gate, IAM at the Door" — API keys authenticate at the Cloud Endpoints gateway, while IAM authorizes at the function level.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Cloud Endpoints with API keys and IAM.
Option B is correct because Cloud Endpoints can authenticate and authorize requests using API keys and IAM, providing fine-grained access control for HTTP-triggered Cloud Functions. Option A is not suitable because VPC connectors are for internal network access, not for authorization. Option C is insecure as URLs can be guessed or leaked. Option D (Firebase Authentication) is designed for mobile client authentication, not for service-to-service authorization.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set a VPC connector and allow only internal traffic.
Why it's wrong here
VPC connector enables private access but does not authenticate callers.
- ✓
Use Cloud Endpoints with API keys and IAM.
Why this is correct
Cloud Endpoints provides robust authentication and authorization for HTTP triggers.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Authentication checks who the user is.
- ✗
Rely on the Cloud Functions URL being unguessable.
Why it's wrong here
URL obscurity is not a security control; URLs can be exposed through logs or leaks.
- ✗
Use Firebase Authentication.
Why it's wrong here
Firebase Authentication is for end-user identity, not for service-to-service calls.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
- Authentication checks who the user is.
- Authorization controls what the user is allowed to do after login.
- Privilege levels affect access to EXEC and configuration commands.
- AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
- Do not assume successful login means full administrative access.
- Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
- Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related PCSE questions on access control and AAA configuration.
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FAQ
Questions learners often ask
What does this PCSE question test?
Authentication checks who the user is.
What is the correct answer to this question?
The correct answer is: Use Cloud Endpoints with API keys and IAM. — Option B is correct because Cloud Endpoints can authenticate and authorize requests using API keys and IAM, providing fine-grained access control for HTTP-triggered Cloud Functions. Option A is not suitable because VPC connectors are for internal network access, not for authorization. Option C is insecure as URLs can be guessed or leaked. Option D (Firebase Authentication) is designed for mobile client authentication, not for service-to-service authorization.
What should I do if I get this PCSE question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related PCSE questions on access control and AAA configuration.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Authentication checks who the user is.
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Last reviewed: Jun 24, 2026
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