MS-900 cheat sheet

Microsoft 365 = Office apps + cloud productivity services (Exchange Online, SharePoint Online, Teams, OneDrive) + Windows and device/identity management depending on plan; Office 365 excludes Windows and most device management.

Every Microsoft 365 and Office 365 enterprise suite includes Teams, SharePoint Online, OneDrive for Business, Exchange Online, and the Office apps.

OneDrive for Business is per-user file storage; SharePoint Online is team/site storage. Moving a shared file from OneDrive to a SharePoint library keeps versioning and permission inheritance intact.

Microsoft 365 Apps for enterprise = locally installed Word, Excel, PowerPoint, Outlook; licensed per user and installable on up to 5 PCs or Macs, 5 tablets, and 5 phones.

Windows 365 is a cloud PC that streams a Windows desktop from Microsoft's cloud; Microsoft 365 E3/E5 instead grant a Windows Enterprise license for locally owned devices.

Power Platform components: Power Apps (apps), Power Automate (workflows), Power BI (analytics), Power Pages (external sites), Copilot Studio (agents).

Exchange Online mailbox size is 50 GB in most plans and 100 GB with E3/E5; shared mailboxes are capped at 50 GB and need no license under 50 GB.

Microsoft 365 Copilot is an add-on license on top of an eligible base plan (E3, E5, Business Standard/Premium) and is not included in any base subscription.

Viva modules map as follows: Connections (communities), Engage (formerly Yammer), Learning, Insights, Goals, Glint - delivered primarily inside Microsoft Teams.

Conditional Access requires Microsoft Entra ID P1, included in Business Premium, E3, and E5; tenants without P1 rely on security defaults, which enforce MFA for all users.

Defender for Office 365 Plan 1 (E3) provides Safe Links, Safe Attachments, and anti-phishing policies; Plan 2 (E5) adds Threat Explorer, automated investigation and response, and attack simulation training.

Microsoft Intune covers MDM (enrollment, configuration, compliance policies) and MAM (app protection policies applied to apps without device enrollment).

Purview sensitivity labels classify and optionally encrypt content, add headers/footers/watermarks, and persist with the file, forming the basis for DLP and auto-labeling.

Retention rules: policies target locations (mailbox, site, Teams), labels target individual items; when rules conflict, retain wins over delete and the longest retention period wins.

eDiscovery Standard ships with E3; eDiscovery Premium (custodians, review sets, near-duplicate detection, graph) requires E5 or an add-on.

Insider Risk Management, Communication Compliance, and Audit Premium are E5-level Purview workloads, not available in E3 base subscriptions.

Zero Trust principles are verify explicitly, use least-privilege access, and assume breach; Microsoft Secure Score quantifies tenant posture and lists prioritized improvement actions.

The Service Trust Portal publishes audit reports, compliance offerings, and the Microsoft Data Protection Addendum used for regulatory evidence.

Business plans (Basic, Standard, Premium) are capped at 300 users; above 300 seats requires Enterprise (E3/E5) or Frontline (F1/F3) plans.

Microsoft 365 Business Premium bundles Entra ID P1, Intune, and Defender for Business but does not grant a Windows Enterprise E3 license.

E3 to E5 delta: Entra ID P2, Defender for Office 365 P2, Defender for Identity and Cloud Apps, eDiscovery Premium, Insider Risk Management, Power BI Pro, and Phone System.

F1/F3 are frontline worker plans using web and mobile Office apps without a full desktop Office install; F3 adds a larger mailbox plus Windows and Intune kiosk capabilities.

The Microsoft 365 Apps plan supplies only the desktop Office applications - it includes no Exchange Online mailbox, Teams, or SharePoint service.

Payment choice: monthly commitment costs more per user but can be cancelled at any time; annual commitment is cheaper and is paid monthly or upfront for the full term.

Trials run 30 days with up to 25 licenses, one trial per plan per tenant; converting to a paid subscription retains all configured data.

Support requests are opened in the Microsoft 365 admin center under Support > New service request, with severity A reserved for critical production outages.

FastTrack is an included benefit for eligible subscriptions (generally 150+ seats) providing remote onboarding, migration, and adoption guidance at no extra cost.