Question 153 of 1,733
MigrationmediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is that both instances are in the same Availability Zone, which defeats the purpose of high availability. For SAP ASCS/ERS high availability across AZs, the architecture must place the ASCS and ERS instances in separate Availability Zones to eliminate a single point of failure; if one zone fails, the other instance can take over. On the AWS Certified SAP on AWS Specialty PAS-C01 exam, this scenario tests your understanding that high availability is about zone-level resilience, not just instance redundancy—a common trap is focusing on instance types or missing security groups, but the core architectural issue is zone placement. Remember the memory tip: “ASCS and ERS must never share a zone—split them to stay alone.”

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.

Exhibit

Refer to the exhibit.

```json
{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "SAP HANA HA using Pacemaker",
  "Resources": {
    "ASCSInstance": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "InstanceType": "m5.large",
        "ImageId": "ami-0abcdef1234567890",
        "SubnetId": "subnet-12345678"
      }
    },
    "ERSInstance": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "InstanceType": "m5.large",
        "ImageId": "ami-0abcdef1234567890",
        "SubnetId": "subnet-12345678"
      }
    }
  }
}

The exhibit shows a CloudFormation template snippet for deploying SAP ASCS and ERS instances. Both instances are launched in the same subnet. What is the main architectural issue with this deployment?

Question 1mediummultiple choice
Review the full subnetting walkthrough →

Exhibit

Refer to the exhibit.

```json
{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "SAP HANA HA using Pacemaker",
  "Resources": {
    "ASCSInstance": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "InstanceType": "m5.large",
        "ImageId": "ami-0abcdef1234567890",
        "SubnetId": "subnet-12345678"
      }
    },
    "ERSInstance": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "InstanceType": "m5.large",
        "ImageId": "ami-0abcdef1234567890",
        "SubnetId": "subnet-12345678"
      }
    }
  }
}

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

Both instances are in the same Availability Zone, which defeats the purpose of high availability

Option A is correct because for high availability, ASCS and ERS should be in different Availability Zones to avoid a single point of failure. Option B is wrong because the instance type is acceptable for a test environment. Option C is wrong because the AMI is not specified, but that is not the main issue. Option D is wrong because there is no security group defined, but that is a security issue, not an architectural HA issue.

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.

  • Both instances are in the same Availability Zone, which defeats the purpose of high availability

    Why this is correct

    HA requires instances in different AZs.

    Related concept

    CIDR notation defines the prefix length.

  • The AMI ID is not specified correctly

    Why it's wrong here

    The AMI ID is a placeholder but not the main issue.

  • The instance type m5.large is too small for SAP

    Why it's wrong here

    m5.large may be sufficient for a small environment.

  • No security group is defined, exposing the instances to the internet

    Why it's wrong here

    Security groups are important but not the main architectural HA issue.

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

An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.

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

Related PAS-C01 practice-question pages

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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: Both instances are in the same Availability Zone, which defeats the purpose of high availability — Option A is correct because for high availability, ASCS and ERS should be in different Availability Zones to avoid a single point of failure. Option B is wrong because the instance type is acceptable for a test environment. Option C is wrong because the AMI is not specified, but that is not the main issue. Option D is wrong because there is no security group defined, but that is a security issue, not an architectural HA issue.

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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Last reviewed: Jun 20, 2026

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