Quick Answer
The answer is AWS WAF, which is the correct service to block IP addresses at the edge of the AWS network. AWS WAF integrates directly with Amazon CloudFront, allowing you to create IP set match conditions that inspect incoming requests before they ever reach your origin, effectively filtering traffic at the CloudFront edge location. For the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of edge-based security versus regional filtering; a common trap is choosing a Network ACL or security group, which operate at the VPC subnet or instance level and cannot block traffic before it enters the AWS network. Remember that for edge blocking, you pair CloudFront with WAF, while for regional blocking behind an Application Load Balancer, WAF also works but lacks the edge benefit. A useful memory tip: think “WAF at the edge, NACL in the region” to distinguish where each filtering layer applies.
This SOA-C02 practice question tests your understanding of networking and content delivery. 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.
An organization wants to block traffic from specific IP addresses at the edge of the AWS network before it reaches the application. Which service should be used?
AWS WAF
Correct. AWS WAF can block IPs at the edge when used with CloudFront or ALB.
Security groups
Why wrong: Security groups are stateful firewalls at the instance/ENI level, not at the edge.
AWS Shield Advanced
Why wrong: Shield Advanced provides DDoS protection but not granular IP blocking.
Network ACLs
Why wrong: NACLs are stateless and apply at the subnet level, not at the edge.
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
AWS WAF integrates with CloudFront and ALB to filter traffic based on IP addresses. For edge blocking, CloudFront with WAF is the best choice.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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
Correct. AWS WAF can block IPs at the edge when used with CloudFront or ALB.
Related concept
Standard ACLs match source addresses.
Security groups
Why it's wrong here
Security groups are stateful firewalls at the instance/ENI level, not at the edge.
AWS Shield Advanced
Why it's wrong here
Shield Advanced provides DDoS protection but not granular IP blocking.
Network ACLs
Why it's wrong here
NACLs are stateless and apply at the subnet level, not at the edge.
Common exam traps
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SOA-C02 ACL questions on filtering logic and placement.
Networking and Content Delivery — study guide chapter
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FAQ
Networking and Content Delivery — This question tests Networking and Content Delivery — Standard ACLs match source addresses..
The correct answer is: AWS WAF — AWS WAF integrates with CloudFront and ALB to filter traffic based on IP addresses. For edge blocking, CloudFront with WAF is the best choice.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SOA-C02 ACL questions on filtering logic and placement.
Standard ACLs match source addresses.
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Last reviewed: Jun 20, 2026
This SOA-C02 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 SOA-C02 exam.
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