AVD Breadth-First Load Balancing and Start VM on Connect

AZ-140 By islever Editorial Last updated

Plan host pools and session hosts

Short answer

D 6 additional users must connect to fill the available capacity on running hosts and trigger Host3 to start via Start VM on connect.

Question

You have an Azure Virtual Desktop deployment that contains a host pool named Pool1. Pool1 has the following settings: • Host pool type: Pooled • Load balancing algorithm: Breadth-first • Max session limit: 5 • Start VM on connect: Yes Pool1 contains the session hosts shown in the following table. How many additional users must connect to Pool1 to start Host3? - Exhibit: AVD Breadth-First Load Balancing and Start VM on Connect
  1. 1
  2. 3
  3. 5
  4. 6 Correct Answer
  5. 10

Key Takeaways

Breadth-first load balancing fills running hosts to their max session limit before Start VM on connect triggers a stopped host, meaning the 6th user connection starts Host3.

This guide explains how Azure Virtual Desktop breadth-first load balancing distributes sessions and triggers the Start VM on connect feature. It establishes that 6 additional users must connect to fill existing session hosts and trigger Host3 to start.

Common mistake: Choosing 5 (Option C) by calculating only the remaining capacity of running hosts, forgetting that the next connection attempt (the 6th user) is actually required to trigger the Start VM on connect feature.

Expert Analysis

Why the Answer Is Correct

With breadth-first load balancing, new user sessions are directed to the session host with the fewest active sessions until all running hosts reach their maximum session limit. Host1 currently has 3 sessions and Host2 has 2 sessions, leaving a combined available capacity of 5 sessions (2 on Host1, 3 on Host2). The first 5 additional users will perfectly fill Host1 and Host2 to their maximum limit of 5 sessions each. Once both running hosts are at capacity, the 6th user attempting to connect will have no available running session hosts. Because the "Start VM on connect" feature is enabled, this 6th connection request triggers the deallocated Host3 to start. Therefore, 6 additional users must connect.

Why the Other Options Are Wrong

Option A (1), B (3), and C (5) incorrectly assume that Host3 starts as soon as capacity is exhausted or miscalculate the remaining capacity. Specifically, Option C (5) represents the exact number of sessions needed to fill the running hosts but fails to account for the fact that an actual connection attempt beyond capacity is the trigger for starting a new VM. Option E (10) likely miscalculates by doubling the max session limit or ignoring the existing sessions entirely.

Community Comment Notes

Commenters debated between 5 and 6 additional users. Some initially chose 5, noting that "Host1 can take 2 more sessions... Host2 can take 3" to reach the limit. However, as another user pointed out after testing, "Just tested, it's D", confirming that the 6th user connection is required to trigger the Start VM on connect process. The key distinction is that filling the capacity (5 users) does not start the VM; the subsequent connection attempt (6th user) does.

Official Reference

https://learn.microsoft.com/en-us/azure/virtual-desktop/start-virtual-machine-on-connect

This link opens the official vendor documentation in a new tab.

Exam Strategy

When calculating users needed to trigger Start VM on connect, first total the remaining capacity of all running hosts. The number of users required to start the next VM is always the remaining capacity plus one, because the feature is triggered by a connection attempt when no running capacity is available.

Community Votes

D
70%
C
30%

70% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 4 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors, not of islever. The comments shown first are the most substantive of the thread — ranked by depth, community endorsement and relevance; expand the list below to read the rest.

From public community threads 4

  1. db7a78f 👍 5 Answered D
    D is correct!!! Given that the maximum session limit is 5 and the load balancing algorithm is set to breadth-first, let’s reassess the situation: Host1 has 3 sessions. Host2 has 2 sessions. Host3 is shut down. With the breadth-first algorithm, new sessions will be distributed evenly across available hosts until they reach their session limits. Since Host1 and Host2 are not yet at their maximum session limit of 5, additional sessions will be assigned to these hosts first. To start Host3, both Host1 and Host2 need to reach their session limit of 5. Currently, Host1 has 3 sessions and Host2 has 2 sessions, so: Host1 needs 2 more sessions to reach 5. Host2 needs 3 more sessions to reach 5. But that will only max out Host 1 and 2 - in order to start Host 3 you would need a 6 user to login. So, the correct answer is: D. 6
  2. jeff1988 👍 2 Answered C
    Currently, Host1 has 3 sessions and Host2 has 2 sessions. Since the load balancing algorithm is set to breadth-first, new sessions will be distributed to the least loaded session host until the max session limit is reached. To start Host3, the existing session hosts (Host1 and Host2) must reach their max session limit of 5 sessions each. Host1 can take 2 more sessions (3 + 2 = 5). Host2 can take 3 more sessions (2 + 3 = 5). Therefore, a total of 5 additional users must connect to Pool1 to start Host3.
  3. db7a78f 👍 1 Answered C
    Given that the maximum session limit is 5 and the load balancing algorithm is set to breadth-first, let’s reassess the situation: Host1 has 3 sessions. Host2 has 2 sessions. Host3 is shut down. With the breadth-first algorithm, new sessions will be distributed evenly across available hosts until they reach their session limits. Since Host1 and Host2 are not yet at their maximum session limit of 5, additional sessions will be assigned to these hosts first. To start Host3, both Host1 and Host2 need to reach their session limit of 5. Currently, Host1 has 3 sessions and Host2 has 2 sessions, so: Host1 needs 2 more sessions to reach 5. Host2 needs 3 more sessions to reach 5. Therefore, a total of 5 additional users must connect to Pool1 to start Host3. So, the correct answer is: C. 5
  4. PeterLabelle 👍 2 Answered D
    Just tested, it's D.

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