The answer is a security group and a network ACL. This is correct because restricting SSH access to a specific IP requires two layers of defense: a security group acts as a stateful virtual firewall at the instance level, automatically allowing return traffic, while a network ACL provides a stateless, subnet-level filter that evaluates rules in numerical order. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this question tests your understanding of the fundamental difference between stateful and stateless filtering, and it is a common trap to choose only one component or to mistakenly select an Internet gateway, which enables connectivity but does not filter by IP. Remember that security groups support “allow” rules only and are stateful, whereas NACLs support both allow and deny rules and are stateless—so for SSH restriction, you configure the NACL inbound rule for your specific IP and the security group inbound rule for TCP port 22. A useful memory tip: “NACL is a net filter, SG is a server guard.”
SOA-C02 Security and Compliance Practice Question
This SOA-C02 practice question tests your understanding of security and compliance. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 SysOps administrator is configuring a new VPC and wants to ensure that only traffic from a specific IP address range can access an EC2 instance via SSH. Which TWO components should be configured? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Network ACL (NACL)
To restrict SSH access to a specific IP range, you configure a network ACL at the subnet level and a security group at the instance level. NACLs are stateless and evaluate rules in order; security groups are stateful. Both can allow inbound SSH from the specific IP range. Internet gateway enables internet access but does not filter by IP. Route tables direct traffic but do not filter. VPC endpoint is for private connectivity to AWS services.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
VPC endpoint
Why it's wrong here
VPC endpoints are used for private connectivity to AWS services, not for filtering SSH access.
✓
Network ACL (NACL)
Why this is correct
NACLs control traffic at the subnet level and can allow/deny inbound SSH from specific IP ranges.
An internet gateway allows internet access but does not filter traffic by source IP.
✗
Route table
Why it's wrong here
Route tables determine where traffic is directed, not whether it is allowed.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
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
How to think about this question
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.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
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
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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Security and Compliance — This question tests Security and Compliance — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Network ACL (NACL) — To restrict SSH access to a specific IP range, you configure a network ACL at the subnet level and a security group at the instance level. NACLs are stateless and evaluate rules in order; security groups are stateful. Both can allow inbound SSH from the specific IP range. Internet gateway enables internet access but does not filter by IP. Route tables direct traffic but do not filter. VPC endpoint is for private connectivity to AWS services.
What should I do if I get this SOA-C02 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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