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PAS-C01 Migration Practice Question

This PAS-C01 practice question tests your understanding of migration. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.

During a migration of an SAP system to AWS, the SAP application team reports that batch jobs are failing with an error 'RFC connection refused'. The on-premises system and AWS are connected via a VPN. What is the MOST likely cause?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "most likely"

    Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Answer choices

Why each option matters

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 attached to the SAP instance does not allow inbound RFC traffic

Security groups act as a virtual firewall for EC2 instances, controlling inbound and outbound traffic. If the security group for the SAP instance does not allow inbound RFC traffic (e.g., on ports 3300 or 3200 for SAP RFC), connections will be refused. Option B (VPN bandwidth) would cause timeouts or slow transfers, not immediate connection refusal. Option C (network ACLs) operates at the subnet level and stateless; they could block RFC ports, but since the error is specifically 'RFC connection refused' and it's a common misconfiguration, security groups are more likely the culprit. Option D (route table) is for routing traffic between networks; if there were no route to on-premises, traffic would not reach AWS at all, rather than being refused.

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 security group attached to the SAP instance does not allow inbound RFC traffic

    Why this is correct

    Security group rules control inbound traffic to the instance.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    CIDR notation defines the prefix length.

  • The VPN bandwidth is insufficient causing timeouts

    Why it's wrong here

    Insufficient bandwidth would cause timeouts, not immediate refusal.

  • The network ACLs are blocking the RFC ports

    Why it's wrong here

    NACLs are stateless and might be an issue, but SGs are more likely.

  • The route table does not have a route to the on-premises network

    Why it's wrong here

    Would cause 'destination unreachable', not 'connection refused'.

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.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

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.

Related practice questions

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FAQ

Questions learners often ask

What does this PAS-C01 question test?

Migration — This question tests Migration — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: The security group attached to the SAP instance does not allow inbound RFC traffic — Security groups act as a virtual firewall for EC2 instances, controlling inbound and outbound traffic. If the security group for the SAP instance does not allow inbound RFC traffic (e.g., on ports 3300 or 3200 for SAP RFC), connections will be refused. Option B (VPN bandwidth) would cause timeouts or slow transfers, not immediate connection refusal. Option C (network ACLs) operates at the subnet level and stateless; they could block RFC ports, but since the error is specifically 'RFC connection refused' and it's a common misconfiguration, security groups are more likely the culprit. Option D (route table) is for routing traffic between networks; if there were no route to on-premises, traffic would not reach AWS at all, rather than being refused.

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.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

CIDR notation defines the prefix length.

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Last reviewed: Jun 20, 2026

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This PAS-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 PAS-C01 exam.