MS-900 Describe Microsoft 365 apps and services Practice Question
This MS-900 practice question tests your understanding of describe microsoft 365 apps and services. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 uses Microsoft Teams and wants to ensure that external users from partner companies can access only specific channels and cannot initiate private chats with internal users. Which Microsoft 365 feature should they configure?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Teams External Access (Federation)
B is correct because Teams External Access (Federation) allows external users from partner organizations to be added to specific channels without granting them full tenant access. It uses the Session Initiation Protocol (SIP) federation model to enable limited collaboration, and administrators can control whether federated users can initiate private chats by disabling the 'External users can contact me' policy in the Teams admin center. This meets the requirement of restricting external users to only designated channels and preventing private chat initiation.
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.
✗
Microsoft Purview Communication Compliance
Why it's wrong here
This monitors communications but does not control access.
✓
Teams External Access (Federation)
Why this is correct
Federation settings control what external users can do, including channel access and chat restrictions.
Related concept
Read the scenario before looking for a memorised answer.
✗
Microsoft Entra B2B collaboration
Why it's wrong here
This is for inviting guests, but the fine-grained control is in Teams external access.
✗
Teams Guest Access
Why it's wrong here
Guest access allows more features, including private chats, and is not as restrictive as federation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Guest Access (which creates full Azure AD guest identities) with External Access (federation), assuming both provide the same level of control, but Guest Access actually grants broader permissions and requires more complex policy management to restrict private chats.
Detailed technical explanation
How to think about this question
Under the hood, Teams External Access uses SIP federation via the Microsoft Teams Federation Service, which relies on DNS SRV records (e.g., _sipfederationtls._tcp.<domain>) to establish trust between tenants. A subtle behavior is that federated users appear as 'External' in the client and cannot be added to teams directly; they must be added to specific channels via the 'Add members' dialog, and their chat capabilities are controlled by the 'Allow federated users to contact me' toggle in the external access settings. In a real-world scenario, a partner company's user can collaborate on a shared channel but cannot see the internal user's presence or start a one-on-one chat unless explicitly allowed.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this MS-900 question in full detail.
Describe Microsoft 365 apps and services — This question tests Describe Microsoft 365 apps and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Teams External Access (Federation) — B is correct because Teams External Access (Federation) allows external users from partner organizations to be added to specific channels without granting them full tenant access. It uses the Session Initiation Protocol (SIP) federation model to enable limited collaboration, and administrators can control whether federated users can initiate private chats by disabling the 'External users can contact me' policy in the Teams admin center. This meets the requirement of restricting external users to only designated channels and preventing private chat initiation.
What should I do if I get this MS-900 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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