Question 1,291 of 2,015

IP Multicast →mediumMatchingObjective-mapped

Quick Answer

The answer is IGMPv2, because it introduced the Leave Group message that triggers a group-specific query from the querier. In IGMPv1, a host simply stops responding to queries, and the router must wait for a timeout to prune the group, which wastes bandwidth. IGMPv2 solves this by having the host send an explicit Leave message, prompting the querier to send a group-specific query to confirm no other members remain before removing the group. On the ENCOR 350-401 exam, this distinction often appears in drag-and-drop tasks comparing IGMP versions, where a common trap is confusing IGMPv2’s querier election (lowest IP address) with IGMPv1’s reliance on a designated router. IGMPv3 adds source filtering with include/exclude lists for SSM, but the key v2 feature is the efficient leave mechanism. Memory tip: v2 “leaves” you with a specific query, while v1 just “waits” for the timeout.

350-401 IP Multicast Practice Question

This 350-401 practice question tests your understanding of ip multicast. 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.

Drag and drop each IGMP version on the left to its matching feature on the right.

Question 1mediummatching

Study the full multicast explanation →

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

✓

IGMPv1: No leave message; querier elected by lowest IP address on subnet

IGMPv1 has no leave message and uses a querier election based on IP address; IGMPv2 adds explicit leave and querier election using lowest IP; IGMPv3 adds source filtering (include/exclude) and supports SSM.

Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.

Common exam traps

Common exam trap: usable hosts are not the same as total addresses

Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.

Detailed technical explanation

How to think about this question

Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.

KKey Concepts to Remember

CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.

TExam Day Tips

Write the block size before choosing the subnet.
Check whether the question asks for hosts, subnets or a specific address range.
Do not confuse /24, /25, /26 and /27 host counts.

Key takeaway

Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.

Real-world example

How this comes up in practice

A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.

What to study next

Got this wrong? Here's your next step.

Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 350-401 subnetting questions on CIDR, address ranges, and subnet selection.

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FAQ

Questions learners often ask

What does this 350-401 question test?

IP Multicast — This question tests IP Multicast — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: IGMPv1: No leave message; querier elected by lowest IP address on subnet — IGMPv1 has no leave message and uses a querier election based on IP address; IGMPv2 adds explicit leave and querier election using lowest IP; IGMPv3 adds source filtering (include/exclude) and supports SSM.

What should I do if I get this 350-401 question wrong?

What is the key concept behind this question?

CIDR notation defines the prefix length.

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Same concept, more angles

1 more ways this is tested on 350-401

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. Drag and drop each IGMP version on the left to its matching feature on the right.

medium

✓ P1.IGMPv1: Uses a query/response model with no leave group message
✓ P2.IGMPv2: Adds leave group messages and querier election
✓ P3.IGMPv3: Adds source filtering (include/exclude lists)
✓ P4.IGMPv2: Supports fast leave by sending a leave group message
✓ P5.IGMPv3: Allows hosts to specify which sources to receive or block

Why P1: IGMPv1 uses a query/response model; IGMPv2 adds leave group messages and querier election; IGMPv3 adds source filtering (include/exclude).

Last reviewed: Jun 18, 2026

Question Discussion

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