Post-Migration Validation
Migration & CoexistencePost-Migration Validation

Post-Migration Validation

20 mins

Understanding the Concept

Post-migration validation ensures all data was migrated successfully and Exchange Online is functioning correctly. Key checks include mail flow testing, client configuration verification, and data completeness validation.

DNS changes are the final cutover step—updating MX records to point to Exchange Online. This should be done during a planned maintenance window with monitoring. SPF, DKIM, and DMARC records must also be updated.

User communication and training are critical for adoption. Provide guidance on accessing Outlook, OWA, and mobile clients. Address common questions about archive access, shared mailbox access, and distribution group management.

Key Points

Validate mail flow with test messages after DNS cutover
Update MX, SPF, DKIM, and DMARC records
Verify client auto-configuration via autodiscover
Check mailbox data completeness (item counts, folder structure)
Test shared mailbox and resource mailbox functionality
Monitor message queues and delivery reports for issues

Why This Matters

Incomplete validation after migration leads to undetected issues that frustrate users and damage IT credibility. Thorough post-migration checks ensure a smooth transition and rapid issue resolution.

Common Mistakes to Avoid

Not updating SPF records after MX record changes
Skipping client auto-configuration testing
Not monitoring mail flow closely in the first 48 hours after cutover

Interview Discussion Points

💡Describe your post-migration validation checklist
💡Explain how to handle post-migration mail flow issues
💡Discuss user communication and training strategies for migration

MS-203 Exam Tips

📝Know the complete DNS change sequence for Exchange Online cutover
📝Understand how to validate mail flow after MX record changes
📝Be familiar with common post-migration issues and their resolutions