CISSP Communication and Network Security Practice Question
This CISSP practice question tests your understanding of communication and network security. 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.
An organization is designing a multicast network for live video streaming. They need to ensure that only authorized receivers can access the multicast group. Which technique should be implemented?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
IGMP filtering
IGMP filtering allows the network to control which hosts are permitted to join a multicast group by filtering IGMP membership reports at the access layer. This ensures that only authorized receivers can become members of the multicast group, providing access control for live video streaming. It is the most direct technique for enforcing authorization at the receiver level.
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.
✓
IGMP filtering
Why this is correct
IGMP filtering restricts which hosts can join multicast groups via IGMP messages.
Related concept
Read the scenario before looking for a memorised answer.
✗
Multicast VLAN registration
Why it's wrong here
MVR is used to distribute multicast streams across VLANs, not for access control.
✗
Static IGMP entries
Why it's wrong here
Manually configuring IGMP entries is not dynamic or scalable for many receivers.
✗
IGMP snooping with port security
Why it's wrong here
IGMP snooping optimizes multicast forwarding but does not enforce authentication.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse IGMP snooping (which optimizes multicast traffic delivery) with IGMP filtering (which enforces access control), leading them to pick IGMP snooping with port security as a security measure when it only controls traffic flooding, not authorization.
Detailed technical explanation
How to think about this question
IGMP filtering works by configuring access control lists (ACLs) on the switch that match IGMPv2 or IGMPv3 membership report messages (type 0x16 or 0x22) and permit or deny them based on source IP, group address, or other criteria. In a real-world scenario, an enterprise streaming sensitive board meetings might use IGMP filtering to allow only specific IP subnets (e.g., executive VLANs) to join the multicast group, while blocking all other hosts at the access switch port level.
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 analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: IGMP filtering — IGMP filtering allows the network to control which hosts are permitted to join a multicast group by filtering IGMP membership reports at the access layer. This ensures that only authorized receivers can become members of the multicast group, providing access control for live video streaming. It is the most direct technique for enforcing authorization at the receiver level.
What should I do if I get this CISSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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