You have an Office 365 subscription. All users have mailboxes hosted in Microsoft Exchange Online. The network administr

[answerhappygod]

You have an Office 365 subscription.
All users have mailboxes hosted in Microsoft Exchange Online.
The network administrators in your organization are updating the network infrastructure, including making changes to the DNS providers and updating the SSL certificates.
You need to perform the following test in the Exchange Online environment:
✑ Verify that the mail exchanger (MX) records for Exchange Online are published correctly.
✑ Send the test message from an external recipient to an Exchange Online recipient.
✑ Verify that the SMTP service is accessible from the Internet.
Which tool should you use?

A. Microsoft Connectivity Analyzer Tool
B. Microsoft Remote Connectivity Analyzer
C. Microsoft Office 365 Client Performance Analyzer
D. Office 365 health, readiness, and connectivity checks