Explanation/Reference:
Explanation:
Microsoft Remote Connectivity Analyzer is a website offered by Microsoft for testing remote connectivity to server services such as Exchange Server, Skype for Business Server and Office 365.
The Office 365 tab on the Remote Connectivity Analyzer has several options for performing different tests regarding Office 365 connectivity. These tests include:
Office 365 General Tests

Microsoft Exchange ActiveSync Connectivity Tests

Microsoft Exchange Web Services Connectivity Tests

Microsoft Office Outlook Connectivity Tests

Internet Email Tests

Mail Flow Configuration

Free/Busy Test

The Office 365 General Tests section includes the following tests:
Office 365 Exchange Domain Server (DNS) Connectivity Test

Office 365 Lync Domain Server (DNS) Connectivity Test

Office 365 Single Sign-OnTest
