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Optimizing service performance →hardMultiple ChoiceObjective-mapped

PCDOE Optimizing service performance Practice Question

This PCDOE practice question tests your understanding of optimizing service performance. 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

Firewall rule JSON:
{
  "name": "deny-high-latency",
  "network": "default",
  "priority": 1000,
  "direction": "INGRESS",
  "sourceRanges": ["0.0.0.0/0"],
  "allow": [{"protocol": "tcp", "ports": ["80","443"]}],
  "deny": [{"protocol": "tcp", "ports": ["80","443"]}],
  "logConfig": {"metadata": "INCLUDE_ALL_METADATA"}
}

Refer to the exhibit. After applying the shown firewall rule, users report increased latency to a web application. 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.

Question 1hardmultiple choice

Full question →

Exhibit

Firewall rule JSON:
{
  "name": "deny-high-latency",
  "network": "default",
  "priority": 1000,
  "direction": "INGRESS",
  "sourceRanges": ["0.0.0.0/0"],
  "allow": [{"protocol": "tcp", "ports": ["80","443"]}],
  "deny": [{"protocol": "tcp", "ports": ["80","443"]}],
  "logConfig": {"metadata": "INCLUDE_ALL_METADATA"}
}

A
The rule priority is set to 1000, which is too low.
Why wrong: Lower priority number means higher precedence; 1000 is default, not problematic.
B
The rule contains both allow and deny for the same traffic, creating a conflict.
A rule cannot have both allow and deny; this misconfiguration likely causes packets to be dropped or processed incorrectly.
C
The source range covers all IPs, causing excessive traffic.
Why wrong: Source range alone does not cause latency.
D
The firewall rule has logging enabled, which adds overhead.
Why wrong: Logging may add minor overhead but not significant latency.

Full breakdown with real-world context →

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 rule contains both allow and deny for the same traffic, creating a conflict.

Correct: The rule has both allow and deny with same ports, and the rule is contradictory; the deny overrides because deny rules are evaluated after allow? Actually in VPC firewall rules, allow and deny cannot both be specified in the same rule. This is an invalid combination. The rule may cause unexpected behavior. Option A is wrong because logging alone does not cause latency. Option B is wrong because source range is all. Option D is wrong because priority is not high.

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.

✗
The rule priority is set to 1000, which is too low.
Why it's wrong here
Lower priority number means higher precedence; 1000 is default, not problematic.
✓
The rule contains both allow and deny for the same traffic, creating a conflict.
Why this is correct
A rule cannot have both allow and deny; this misconfiguration likely causes packets to be dropped or processed incorrectly.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The source range covers all IPs, causing excessive traffic.
Why it's wrong here
Source range alone does not cause latency.
✗
The firewall rule has logging enabled, which adds overhead.
Why it's wrong here
Logging may add minor overhead but not significant latency.

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 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 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 PCDOE NAT questions on configuration and troubleshooting.

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FAQ

Questions learners often ask

What does this PCDOE question test?

Optimizing service performance — This question tests Optimizing service performance — Static NAT maps one inside address to one outside address..

What is the correct answer to this question?

The correct answer is: The rule contains both allow and deny for the same traffic, creating a conflict. — Correct: The rule has both allow and deny with same ports, and the rule is contradictory; the deny overrides because deny rules are evaluated after allow? Actually in VPC firewall rules, allow and deny cannot both be specified in the same rule. This is an invalid combination. The rule may cause unexpected behavior. Option A is wrong because logging alone does not cause latency. Option B is wrong because source range is all. Option D is wrong because priority is not high.

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

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?

Static NAT maps one inside address to one outside address.

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Last reviewed: Jun 24, 2026

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