Question 235 of 509

Quick Answer

The answer is to switch from synchronous replication to asynchronous mode with continuous data protection (CDP). Synchronous replication over a 500 km link introduces 15 ms latency, which forces the primary database to wait for write acknowledgments from the DR site, degrading performance under peak load and causing the RTO miss. Asynchronous replication eliminates this latency impact on the primary site, while CDP captures every write change continuously, ensuring the 15-minute RPO is met even if the last few seconds of data are lost. This scenario tests your understanding of the trade-off between synchronous and asynchronous replication in the CISA exam—specifically, that distance-induced latency cannot be fixed by bandwidth upgrades, and that CDP is the only method that guarantees near-zero data loss without slowing production. A common trap is assuming more bandwidth solves latency; it does not, because latency is a propagation delay, not a throughput issue. Memory tip: “Sync is for short hops; async with CDP bridges the gap.”

CISA Practice Question: Information Systems Operations and Business Resilience

This CISA practice question tests your understanding of information systems operations and business resilience. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 multinational organization operates a critical ERP system on a virtualized infrastructure across two data centers (primary and DR). The primary data center is located in Region A, and the DR site in Region B, 500 km away. The ERP database is 2 TB and changes at an average rate of 10 MB per second. The organization uses synchronous replication between the two sites over a dedicated 10 Gbps WAN link. During a recent disaster simulation, the IT team observed that the replication link experienced 15 ms latency, causing the primary database to slow down significantly under peak load, ultimately missing the defined RTO of 4 hours for full failover. The business has an RPO of 15 minutes. The CISO asks the IS auditor to recommend a solution that balances cost and performance while meeting both RTO and RPO. Which of the following is the BEST course of action?

Clue words in this question

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

  • Clue: "best"

    Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

  • Clue: "primary"

    Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

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

Change replication to asynchronous mode and implement continuous data protection (CDP) to meet the 15-minute RPO.

Synchronous replication over long distance introduces latency that degrades primary performance. Changing to asynchronous replication with continuous data protection (CDP) can meet the 15-minute RPO without impacting the primary site. Upgrading bandwidth does not reduce latency; backup-to-disk with hourly logs may not meet RPO due to potential data loss; reducing RPO changes the business requirement unacceptably.

Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Change replication to asynchronous mode and implement continuous data protection (CDP) to meet the 15-minute RPO.

    Why this is correct

    Correct: Asynchronous replication eliminates performance impact, and CDP provides point-in-time recovery within RPO.

    Clue confirmation

    The clue words "best", "primary" in the question point toward this answer.

    Related concept

    Static NAT maps one inside address to one outside address.

  • Reduce the RPO to 30 minutes and perform snapshots every 30 minutes on the primary site.

    Why it's wrong here

    Changing RPO alters business requirement without solving the replication issue.

  • Upgrade the WAN link to 40 Gbps to reduce latency and improve replication throughput.

    Why it's wrong here

    Bandwidth upgrade does not reduce propagation latency; 15 ms is distance-limited.

  • Implement a backup-to-disk solution with daily full backups and hourly transaction log backups to the DR site.

    Why it's wrong here

    Hourly backups may not meet a 15-minute RPO, and full daily backups require longer recovery.

Common exam traps

Common exam trap: NAT rules depend on direction and matching traffic

NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.

Detailed technical explanation

How to think about this question

NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.

KKey Concepts to Remember

  • Static NAT maps one inside address to one outside address.
  • PAT allows many inside hosts to share one public address using ports.
  • Inside local and inside global describe the private and translated addresses.
  • NAT ACLs identify traffic for translation, not always security filtering.

TExam Day Tips

  • Identify inside and outside interfaces first.
  • Check whether the scenario needs static NAT, dynamic NAT or PAT.
  • Do not confuse NAT matching ACLs with normal packet-filtering intent.

Key takeaway

NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.

Real-world example

How this comes up in practice

A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.

What to study next

Got this wrong? Here's your next step.

Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CISA NAT questions on configuration and troubleshooting.

Related practice questions

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FAQ

Questions learners often ask

What does this CISA question test?

Information Systems Operations and Business Resilience — This question tests Information Systems Operations and Business Resilience — Static NAT maps one inside address to one outside address..

What is the correct answer to this question?

The correct answer is: Change replication to asynchronous mode and implement continuous data protection (CDP) to meet the 15-minute RPO. — Synchronous replication over long distance introduces latency that degrades primary performance. Changing to asynchronous replication with continuous data protection (CDP) can meet the 15-minute RPO without impacting the primary site. Upgrading bandwidth does not reduce latency; backup-to-disk with hourly logs may not meet RPO due to potential data loss; reducing RPO changes the business requirement unacceptably.

What should I do if I get this CISA question wrong?

Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CISA NAT questions on configuration and troubleshooting.

Are there clue words in this question I should notice?

Yes — watch for: "best", "primary". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

What is the key concept behind this question?

Static NAT maps one inside address to one outside address.

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Last reviewed: Jun 24, 2026

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