SharePoint Online Sites and Architecture Field Guide

What this guide covers

SharePoint Online is the content substrate the rest of Microsoft 365 runs on. Teams file tabs, OneDrive sync, Purview retention, Entra guest access, they all touch a SharePoint site at some point, usually one that got provisioned automatically when someone created a group and never thought about again. The Learn documentation describes each piece accurately and in isolation. What it does not do is connect them, and the gaps between those pages are exactly where production breaks.

The defaults are the problem. You clear the self-service site creation checkbox, feel safe, then watch a site appear the next time someone spins up a Team. You flip storage from manual back to automatic and silently lose every per-site quota you set. You restore a deleted group site on day 45 and find the mailbox and Teams are already gone, because the group recycle window is 30 days and the site window is 93. None of that is a bug. It is documented behavior scattered across a hundred pages that no one reads in order.

This book is the connected account: service model, site types and their exact WebTemplate codes, hubs, provisioning, storage math, and lifecycle wired together, with each failure mode named before you hit it. Every limit, license boundary, and admin path is grounded against current Microsoft Learn and validated in a live Microsoft 365 E5 lab. A trial tenant is enough to follow along; you do not need a production estate.

Chapter map

1. SharePoint Online in the Microsoft 365 Ecosystem
2. Licensing, Roles, and Prerequisites
3. Modern vs. Classic Experience, What Admins Must Know
4. Site Types, Team Sites, Communication Sites, Channel Sites, and the Home Site
5. Microsoft 365 Groups, Teams, and OneDrive, How SharePoint Underpins Them
6. Flat Architecture and Hub Sites, Planning and Design
7. Creating and Registering Hub Sites
8. Site Provisioning, Self-Service Controls and the Provisioning Pipeline
9. Site Templates and Site Scripts
10. The Home Site, Global Navigation, and the SharePoint App Bar
11. Storage, Pooled, Manual, and Per-Site Limits
12. Site Lifecycle, Ownership, Inactivity, Deletion, Restore, and Address Changes
13. Before You Go to Production, Admin Center Mastery and Architecture Checklist

Appendices: PowerShell and Graph Quick Reference; Build a Lab Tenant; Production Readiness Checklist.

Who it is for

This is for SharePoint and Microsoft 365 administrators and engineers who run a real tenant and want the moving parts connected rather than listed, for IT pros ramping onto SharePoint Online who need one coherent production reference, and for anyone studying MS-700 (Managing Microsoft Teams), where SharePoint shows up precisely because Teams is built on it, who wants depth past exam cramming.

See where you are

7 questions from this guide's territory (3 easy, 4 medium), with the explanation after each. Nothing is stored and nothing is sent anywhere.

The rest of SharePoint Online Field Guides

One product per book, a lab appendix in every one, and a companion page like this one for each.

• 
  Field guide

  SharePoint Online Administration and Migration Field Guide

  SharePoint Online has no servers for you to patch, which is exactly why its failures are harder to find.

  Kindle$12.99Get it on AmazonCompanion page
• 
  Field guide

  SharePoint Online Content, Metadata, and Search Field Guide

  The column nobody indexed. The term set left open.

  Publishing$12.99Companion page
• 
  Field guide

  SharePoint Online Governance, Security, and Compliance Field Guide

  Nothing in SharePoint compliance breaks loudly.

  Kindle$12.99Get it on AmazonCompanion page
• 
  Field guide

  SharePoint Online Permissions and Sharing Field Guide

  You can build a textbook-correct site permission model and still watch an Anyone link walk a document out to an unauthenticated stranger.

  Kindle$12.99Get it on AmazonCompanion page

The hard set (2 questions)

The hardest SharePoint questions this guide publishes, none of them repeated from the placement quiz above: the answer first, why every other option is wrong, and the Microsoft Learn page behind it. The practice book for this exam holds the full bank.

Contoso's tenant was created in 2017, so the root site at https://contoso.sharepoint.com is a classic team site. The administrator wants a modern intranet landing page at the root URL using the Replace site (site swap) operation in the SharePoint admin center. Which candidate satisfies the documented requirements for the incoming site?

Correct answer: B. A communication site (SITEPAGEPUBLISHING#0) on which the publishing feature has never been activated and which is neither a hub site nor associated with any hub.

Microsoft Learn lists the site swap limitations: the new root site must be a communication site (SITEPAGEPUBLISHING#0) or a modern team site that is not connected to a Microsoft 365 group (STS#3), and one where the publishing feature has never been activated. Additionally, when replacing the root site, neither the current site nor the new site can be hub sites or associated with a hub; hubs must be unregistered (or sites disassociated) first, then re-registered after the swap. The root site itself cannot be deleted and cannot be connected to a Microsoft 365 group, which is why swap is the supported replacement path.

Why the other options are wrong:

• A. Classic publishing sites are not a supported incoming template, and any site where the publishing feature was ever activated is disqualified even if it has since been dressed up with modern pages.
• C. Neither the current root nor the incoming site can be a hub or associated with a hub at swap time. A hub must be unregistered before the swap and re-registered afterward; hub status does not carry through.
• D. Group-connected team sites are not eligible incoming sites. Only communication sites or modern team sites without a Microsoft 365 group qualify, and the root site can never be group-connected.

Memory hook: Root swap wants a clean modern site: a comm site or groupless modern team site, publishing never touched, no hub strings attached on either side.

Microsoft Learn: Modern root site

A site template references site scripts that together contain 120 actions. When an administrator applies it with Invoke-SPOSiteDesign, the run fails, but applying the same template through the site's UI succeeds. What explains the difference?

Correct answer: C. Invoke-SPOSiteDesign applies scripts synchronously and is capped at 30 actions; the UI (and Add-SPOSiteDesignTask) apply asynchronously with a 300-action / 100,000-character limit.

Applying a site design synchronously via Invoke-SPOSiteDesign is capped at 30 actions/subactions. Applying it asynchronously - through the UI or Add-SPOSiteDesignTask - raises the limit to 300 actions (or 100,000 characters), so a 120-action design succeeds there.

Why the other options are wrong:

• A. The UI doesn't batch behind the scenes; it applies asynchronously under a higher single limit.
• B. The synchronous cap is 30 (not 100) and the asynchronous cap is 300 (not 120).
• D. Invoke-SPOSiteDesign supports team, communication, and other supported templates; template type is not the cause.

Memory hook: 30 sync (Invoke), 300 async (Task/UI).

Microsoft Learn: Site design overview