The correct answer is that the security group for the SAProuter instance does not allow inbound traffic from the Network Load Balancer (NLB). This is because an NLB operates at layer 4 and preserves the source IP of the client, meaning the SAProuter instance must have a security group rule explicitly permitting inbound TCP port 3298 from the NLB’s private IP addresses or subnet CIDR—not from the internet-facing clients directly. On the AWS Certified SAP on AWS Specialty PAS-C01 exam, this scenario tests your understanding of how security groups interact with load balancers and the specific port requirements for SAProuter connections. A common trap is assuming the NAT gateway or Direct Connect is the issue, but those handle outbound or on-premises traffic, not inbound SAP support access through the NLB. Memory tip: think “NLB sends real IPs, so the security group must welcome them on port 3298.”
PAS-C01 Technology Practice Question
This PAS-C01 practice question tests your understanding of technology. 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 SAP system uses AWS Direct Connect to connect to on-premises networks. The SAP application servers are in a private subnet with a NAT gateway for outbound internet. The SAProuter instance is behind an Internet-facing Network Load Balancer (NLB). Connections from SAP support to the SAProuter timeout. What is the likely cause?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The security group for the SAProuter instance does not allow inbound traffic from the NLB.
Option D is correct because SAProuter requires TCP port 3298 to be open. Option A (NATgateway) is for outbound traffic. Option B (Direct Connect) is for on-premises. Option C (security group) is important but not the most specific cause.
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.
✗
The NLB target group is configured with the wrong protocol or port for SAProuter.
Why it's wrong here
The NLB target group should use TCP port 3298; misconfiguration would cause timeouts.
✓
The security group for the SAProuter instance does not allow inbound traffic from the NLB.
Why this is correct
This is a possible cause, but the question asks for the most specific cause given the symptom.
The Direct Connect virtual interface is not advertising the SAProuter's IP address.
Why it's wrong here
Direct Connect is for on-premises connectivity, not internet.
✗
The NAT gateway does not allow inbound traffic from the internet.
Why it's wrong here
NATgateway is for outbound only; inbound is not needed.
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 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
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 PAS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
Technology — This question tests Technology — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The security group for the SAProuter instance does not allow inbound traffic from the NLB. — Option D is correct because SAProuter requires TCP port 3298 to be open. Option A (NAT gateway) is for outbound traffic. Option B (Direct Connect) is for on-premises. Option C (security group) is important but not the most specific cause.
What should I do if I get this PAS-C01 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 PAS-C01 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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