The answer is the Set-OrganizationConfig cmdlet with the -DefaultMailboxSize parameter. This is correct because the default mailbox storage limit for new users in Exchange Online is an organization-wide setting that applies only to mailboxes created after the change, overriding the standard 50 GB limit for Microsoft 365 E3 licenses. The Exchange admin center and Microsoft 365 admin center do not expose this specific default quota for new mailboxes, making PowerShell the only tool to modify it. On the MS-102 exam, this tests your understanding of tenant-level configuration versus per-user settings, and a common trap is confusing this with Set-Mailbox or the admin center quota options. Remember the mnemonic: “Org config sets the default size for new guys” — think of the OrganizationConfig cmdlet as the master switch for all future mailboxes.
MS-102 Deploy and manage a Microsoft 365 tenant Practice Question
This MS-102 practice question tests your understanding of deploy and manage a microsoft 365 tenant. 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 company has just purchased Microsoft 365 E3 licenses. They want to configure the default mailbox storage limit for all new users. Which setting should they modify?
Option C is correct because the default mailbox storage limit for all new users in Exchange Online is configured via the Set-OrganizationConfig cmdlet with the -DefaultMailboxSize parameter. This setting applies to mailboxes created after the change, overriding the default 50 GB limit for Microsoft 365 E3 licenses. The Exchange admin center and Microsoft 365 admin center do not expose this specific default quota setting for new mailboxes.
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.
This cmdlet sets the default mailbox size for all new users in the organization.
Related concept
Read the scenario before looking for a memorised answer.
✗
Microsoft 365 admin center -> Org settings -> Mailbox storage
Why it's wrong here
There is no 'Mailbox storage' option under Org settings in the Microsoft 365 admin center.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the default mailbox quota can be set via the Exchange admin center's 'default mailbox quota' option, but that setting applies to mailbox databases in on-premises Exchange, not Exchange Online, where the default is controlled at the organization level via PowerShell.
Detailed technical explanation
How to think about this question
The Set-OrganizationConfig -DefaultMailboxSize parameter sets the default mailbox size in bytes (e.g., 53687091200 for 50 GB) for new mailboxes created after the change. This is stored in the organization's configuration object in Exchange Online and applies to all new mailboxes regardless of license type, though E3 licenses include a 100 GB mailbox limit by default. A subtle behavior is that this setting does not retroactively affect existing mailboxes; you must use Set-Mailbox to modify quotas for existing users.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this MS-102 question in full detail.
Deploy and manage a Microsoft 365 tenant — This question tests Deploy and manage a Microsoft 365 tenant — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Exchange Online PowerShell: Set-OrganizationConfig -DefaultMailboxSize — Option C is correct because the default mailbox storage limit for all new users in Exchange Online is configured via the Set-OrganizationConfig cmdlet with the -DefaultMailboxSize parameter. This setting applies to mailboxes created after the change, overriding the default 50 GB limit for Microsoft 365 E3 licenses. The Exchange admin center and Microsoft 365 admin center do not expose this specific default quota setting for new mailboxes.
What should I do if I get this MS-102 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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