Explanation

References:
https://docs.microsoft.com/en-us/intune/apps/app-protection-policy

Topic 2, Fabrikam inc.
Overview
Fabrikam, Inc. is manufacturing company that sells products through partner retail stores. Fabrikam has 5,000 employees located in offices throughout Europe.
Existing Environment
Network Infrastructure
The network contains an Active Directory forest named fabrikam.com. Fabrikam has a hybrid Microsoft Azure Active Directory (Azure AD) environment.
The company maintains some on-premises servers for specific applications, but most end-user applications are provided by a Microsoft 365 E5 subscription.
Problem Statements
Fabrikam identifies the following issues:
* Since last Friday, the IT team has been receiving automated email messages that contain "Unhealthy Identity Synchronization Notification" in the subject line.
* Several users recently opened email attachments that contained malware. The process to remove the malware was time consuming.
Requirements
Planned Changes
Fabrikam plans to implement the following changes:
* Fabrikam plans to monitor and investigate suspicious sign-ins to Active Directory
* Fabrikam plans to provide partners with access to some of the data stored in Microsoft 365 Application Administration Fabrikam identifies the following application requirements for managing workload applications:
* User administrators will work from different countries
* User administrators will use the Azure Active Directory admin center
* Two new administrators named Admin1 and Admin2 will be responsible for managing Microsoft Exchange Online only Security Requirements Fabrikam identifies the following security requirements:
* Access to the Azure Active Directory admin center by the user administrators must be reviewed every seven days. If an administrator fails to respond to an access request within three days, access must be removed
* Users who manage Microsoft 365 workloads must only be allowed to perform administrative tasks for up to three hours at a time. Global administrators must be exempt from this requirement
* Users must be prevented from inviting external users to view company data. Only global administrators and a user named User1 must be able to send invitations
* Azure Advanced Threat Protection (ATP) must capture security group modifications for sensitive groups, such as Domain Admins in Active Directory
* Workload administrators must use multi-factor authentication (MFA) when signing in from an anonymous or an unfamiliar location
* The location of the user administrators must be audited when the administrators authenticate to Azure AD
* Email messages that include attachments containing malware must be delivered without the attachment
* The principle of least privilege must be used whenever possible

See explanation below.
Explanation
You need to configure the Sharing options in the SharePoint admin center.
* Go to the SharePoint admin Center.
* Navigate to Policies > Sharing.
* In the External Sharing section, click on More external sharing settings.
* Tick the Limit external sharing by domain
* Click the Add domains button.
* Select the Allow only specific domains option and type in the domain contoso.com.
* Click Save to save the changes.

Reference:
https://docs.microsoft.com/en-us/azure/active-directory/users-groups-roles/groups-dynamic-membership#supported-values

Explanation