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CISM Practice Question: Refer to the exhibit

Exhibit

Refer to the exhibit.

Access Control List (ACL) on border router:

access-list 100 deny ip 10.0.0.0 0.255.255.255 any
access-list 100 deny ip 172.16.0.0 0.15.255.255 any
access-list 100 deny ip 192.168.0.0 0.0.255.255 any
access-list 100 deny ip 127.0.0.0 0.255.255.255 any
access-list 100 deny ip 0.0.0.0 0.255.255.255 any
access-list 100 permit ip any any

Refer to the exhibit. A security analyst reviews the ACL on the organization's border router. Based on the exhibit, which of the following is the MOST significant governance concern?

⚠ Common exam trap

The trap here is that candidates focus on the inbound ACL's content (denying private IPs) and miss the governance issue of missing outbound anti-spoofing controls, which is a classic CISM governance concern about policy compliance rather than just ACL syntax.

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 ACL does not include filtering for outbound traffic, which may allow spoofed internal IPs to exit the network.

The ACL shown only filters inbound traffic on the border router's external interface. Without an outbound ACL (or an inbound ACL on the internal interface), spoofed packets with internal source IP addresses can exit the network, enabling IP spoofing attacks that bypass anti-spoofing best practices (RFC 2827, BCP 38). This is a governance concern as it violates the principle of preventing source address spoofing, which is a fundamental security control for network perimeter defense.

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 ACL is applied to the outbound interface, which is ineffective for blocking inbound attacks.

    Why it's wrong here

    The exhibit does not specify direction, but the ACL is likely applied inbound; even if outbound, the governance concern is the missing outbound filtering.

  • ✓

    The ACL does not include filtering for outbound traffic, which may allow spoofed internal IPs to exit the network.

    Why this is correct

    Outbound filtering (ingress filtering) is missing, which is a governance oversight.

  • ✗

    The ACL permits any traffic after denying specific IP ranges, creating a security gap.

    Why it's wrong here

    The permit any any at the end is standard after denying specific ranges; it does not create a gap by itself.

  • ✗

    The ACL permits all traffic from private IP addresses, which could allow internal IP spoofing.

    Why it's wrong here

    The ACL denies private IP addresses inbound, so this is not a concern.

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

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

This CISM practice question is part of Courseiva's free ISACA 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 CISM exam.