Question 87 of 537
Manage securityhardMultiple ChoiceObjective-mapped

Configure firewalld to Allow Forwarding from Internal to DMZ Zone

This EX200 practice question tests your understanding of manage security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 Red Hat Enterprise Linux 9 system is configured as a router between an internal network (10.0.1.0/24) and a DMZ network (10.0.2.0/24). IP forwarding is enabled, and firewalld is active. The internal interface (eth0) is assigned to the 'internal' firewall zone, and the DMZ interface (eth1) is assigned to the 'dmz' zone. The requirement is that hosts on the internal network should be able to initiate connections to hosts in the DMZ, but the DMZ should not be able to initiate connections to the internal network. The administrator finds that traffic from internal to DMZ is being blocked. The internal zone has 'masquerade' enabled, and the dmz zone has no special settings. What is the most likely cause of the blocked traffic?

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 internal zone is missing a rule to allow forwarded traffic to the DMZ

The internal zone is missing a rule to allow forwarded traffic to the DMZ. By default, firewalld zones have a default target of 'default' or 'reject', which drops forwarded traffic that does not match an explicit allow rule. Even though IP forwarding is enabled and the internal zone has masquerade, the firewall still filters forwarded packets based on zone rules. To permit traffic from internal to DMZ, a rule such as 'firewall-cmd --zone=internal --add-rich-rule="rule family=ipv4 forward-port port=any protocol=tcp to-port=any"' or more commonly a direct forward rule or policy object must be added to allow the forwarded traffic.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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 dmz zone should be assigned to the internal interface

    Why it's wrong here

    That would incorrectly group both interfaces into one zone, defeating the separation of security levels.

  • The internal zone is missing a rule to allow forwarded traffic to the DMZ

    Why this is correct

    By default, firewalld zones drop forwarded traffic between zones unless a policy or direct rule allows it. Adding a rich rule or using policy-based forwarding is needed.

    Clue confirmation

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

    Related concept

    Read the scenario before looking for a memorised answer.

  • The internal zone has masquerade enabled, which is incorrect for a router

    Why it's wrong here

    Masquerade might be unnecessary, but it alone does not block traffic; it would change source IPs, potentially breaking routing.

  • The dmz zone does not have masquerade enabled

    Why it's wrong here

    Masquerade is for source NAT on outgoing traffic; it is not required for routing between directly connected networks.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often assume enabling IP forwarding and masquerade is sufficient for routing between zones, but they overlook that firewalld's zone-based filtering blocks forwarded traffic by default unless an explicit forward rule or policy is configured.

Detailed technical explanation

How to think about this question

In firewalld, forwarded traffic between zones is subject to the zone's 'forward' rules, which are separate from input/output rules. The default policy for forwarded traffic in most zones is 'reject', meaning that without an explicit forward rule, packets crossing from one zone to another are dropped. This behavior is controlled by the 'forward' target in the zone's XML configuration, and can be overridden with rich rules or direct rules. In RHEL 9, the recommended approach is to use firewalld policies (e.g., 'firewall-cmd --new-policy internal-to-dmz --add-ingress-zone internal --add-egress-zone dmz --set-target ACCEPT') to explicitly allow inter-zone forwarding.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.

Visual reference

Source Router + ACL permit 10.0.0.0/8 deny any Server 10.0.0.5 ✓ 192.168.1.1 ✗ dropped ACLs evaluate top-down; first match wins — implicit deny all at end

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this EX200 question test?

Manage security — This question tests Manage security — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The internal zone is missing a rule to allow forwarded traffic to the DMZ — The internal zone is missing a rule to allow forwarded traffic to the DMZ. By default, firewalld zones have a default target of 'default' or 'reject', which drops forwarded traffic that does not match an explicit allow rule. Even though IP forwarding is enabled and the internal zone has masquerade, the firewall still filters forwarded packets based on zone rules. To permit traffic from internal to DMZ, a rule such as 'firewall-cmd --zone=internal --add-rich-rule="rule family=ipv4 forward-port port=any protocol=tcp to-port=any"' or more commonly a direct forward rule or policy object must be added to allow the forwarded traffic.

What should I do if I get this EX200 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jul 4, 2026

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This EX200 practice question is part of Courseiva's free Red Hat 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 EX200 exam.