Quick Answer
The correct answer is an inbound rule allowing TCP port 443 from 0.0.0.0/0. This is required because the Application Load Balancer terminates HTTPS traffic, meaning it handles the TLS handshake and decryption before forwarding requests to the backend EC2 instances. The security group attached to the ALB must explicitly permit inbound traffic on port 443 from any source (0.0.0.0/0) to allow clients to establish encrypted connections over the internet. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this concept tests your understanding of how security groups control traffic at the load balancer level versus the instance level, often appearing in scenario-based questions about securing web tiers. A common trap is confusing the ALB’s inbound rule with the backend instance security group—remember, the ALB needs port 443 open to the world, while the instances only need to accept traffic from the ALB’s security group on the application port. Memory tip: “ALB listens on 443 for the world; instances listen only on the ALB’s word.”
This ANS-C01 practice question tests your understanding of network management and operations. 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 company is deploying a web application on EC2 instances behind an ALB. The application must be accessible only over HTTPS. Which security group rule should be added to the ALB security group?
Inbound: TCP port 22 from 0.0.0.0/0
Why wrong: Port 22 is SSH.
Inbound: TCP port 443 from 0.0.0.0/0
HTTPS uses port 443.
Inbound: TCP port 3306 from 0.0.0.0/0
Why wrong: Port 3306 is MySQL database.
Inbound: TCP port 80 from 0.0.0.0/0
Why wrong: Port 80 is HTTP, not HTTPS.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Inbound: TCP port 443 from 0.0.0.0/0
The ALB must terminate HTTPS traffic, which requires an inbound rule allowing TCP port 443 (HTTPS) from 0.0.0.0/0. This ensures clients can establish encrypted TLS connections to the load balancer, as the application is only accessible over HTTPS.
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.
Inbound: TCP port 22 from 0.0.0.0/0
Why it's wrong here
Port 22 is SSH.
Inbound: TCP port 443 from 0.0.0.0/0
Why this is correct
HTTPS uses port 443.
Related concept
Read the scenario before looking for a memorised answer.
Inbound: TCP port 3306 from 0.0.0.0/0
Why it's wrong here
Port 3306 is MySQL database.
Inbound: TCP port 80 from 0.0.0.0/0
Why it's wrong here
Port 80 is HTTP, not HTTPS.
Common exam traps
AWS often tests the distinction between the ALB's security group (which needs port 443 for HTTPS) and the EC2 instances' security group (which needs only the ALB's source security group), leading candidates to mistakenly choose port 80 (HTTP) or port 22 (SSH) for the ALB.
Detailed technical explanation
Under the hood, the ALB acts as a TLS termination proxy: it decrypts HTTPS traffic on port 443, inspects the request, and forwards it to the target group over HTTP (or HTTPS) on a private subnet. The security group rule for port 443 must be present on the ALB's security group, not the EC2 instances' security group, as the ALB handles the client-facing encryption. In real-world scenarios, you might also add a rule to restrict inbound traffic to specific CIDR ranges (e.g., corporate IPs) instead of 0.0.0.0/0 for enhanced security, but the question's requirement for public HTTPS access makes 0.0.0.0/0 appropriate.
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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Management and Operations — study guide chapter
Learn the concepts, then practise the questions
Network Management and Operations practice questions
Targeted practice on this topic area only
All ANS-C01 questions
1,705 questions across all exam domains
AWS Certified Advanced Networking Specialty ANS-C01 study guide
Full concept coverage aligned to exam objectives
ANS-C01 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise ANS-C01 questions linked to Network Management and Operations.
Practise ANS-C01 questions linked to Network Security, Compliance and Governance.
Practise ANS-C01 questions linked to Network Design.
Practise ANS-C01 questions linked to Network Implementation.
Practise ANS-C01 questions linked to ANS-C01 fundamentals.
Practise ANS-C01 questions linked to ANS-C01 scenario.
Practise ANS-C01 questions linked to ANS-C01 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Network Management and Operations — This question tests Network Management and Operations — Read the scenario before looking for a memorised answer..
The correct answer is: Inbound: TCP port 443 from 0.0.0.0/0 — The ALB must terminate HTTPS traffic, which requires an inbound rule allowing TCP port 443 (HTTPS) from 0.0.0.0/0. This ensures clients can establish encrypted TLS connections to the load balancer, as the application is only accessible over HTTPS.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 30, 2026
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services 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 ANS-C01 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.