Quick Answer
The answer is AWS WAF, because it is the only service among the options that can block traffic by geographic region when associated with an internet-facing Application Load Balancer. AWS WAF uses geo-match conditions in its web ACLs to inspect the source IP’s country code, allowing you to create rules that deny or allow requests from specific countries. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this question tests your understanding of where layer 7 filtering capabilities reside versus network-layer controls. A common trap is confusing Security Groups or Network ACLs with WAF, but remember that Security Groups and NACLs operate at layers 3 and 4 and have no concept of geographic location. AWS Shield Advanced, while valuable for DDoS mitigation, does not provide granular geographic filtering. For the exam, a useful memory tip is: “WAF watches the world; Security Groups see only IPs.”
This ANS-C01 practice question tests your understanding of network security, compliance and governance. 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 has a VPC with an internet-facing Application Load Balancer (ALB) that routes traffic to EC2 instances in private subnets. The security team wants to block traffic from specific geographic regions. Which AWS service should they use?
AWS WAF
WAF can create geo-match conditions to block traffic from specific countries.
AWS Shield Advanced
Why wrong: Shield Advanced protects against DDoS attacks, not geographic filtering.
Network ACLs
Why wrong: NACLs filter by IP addresses and ports, not geography.
Security Groups
Why wrong: Security groups can only filter by IP addresses, not geography.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AWS WAF
Option A is correct because AWS WAF can be associated with an ALB to filter traffic based on geographic location. Option B is wrong because Security Groups do not support geographic blocking. Option C is wrong because Network ACLs do not support geographic blocking. Option D is wrong because AWS Shield Advanced provides DDoS protection, not geographic filtering.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
AWS WAF
Why this is correct
WAF can create geo-match conditions to block traffic from specific countries.
Related concept
CIDR notation defines the prefix length.
AWS Shield Advanced
Why it's wrong here
Shield Advanced protects against DDoS attacks, not geographic filtering.
Network ACLs
Why it's wrong here
NACLs filter by IP addresses and ports, not geography.
Security Groups
Why it's wrong here
Security groups can only filter by IP addresses, not geography.
Common exam traps
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Network Security, Compliance and Governance — This question tests Network Security, Compliance and Governance — CIDR notation defines the prefix length..
The correct answer is: AWS WAF — Option A is correct because AWS WAF can be associated with an ALB to filter traffic based on geographic location. Option B is wrong because Security Groups do not support geographic blocking. Option C is wrong because Network ACLs do not support geographic blocking. Option D is wrong because AWS Shield Advanced provides DDoS protection, not geographic filtering.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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Last reviewed: Jun 20, 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.
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