Migrate SQL Server with TDE to Azure SQL Managed Instance Using DMS Online
You are migrating an on-premises SQL Server 2012 database to Azure SQL Managed Instance. The database is 5 TB and uses Transparent Data Encryption (TDE) with a certificate stored in the local machine store. What is the best approach to migrate while preserving TDE?
⚠ Common exam trap
It's easy for candidates to assume TDE certificates are automatically transferred or that disabling TDE is a safe shortcut, but in reality, the certificate must be explicitly backed up and restored to the target before the database restore can succeed.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Back up the certificate and private key to a .pfx file, restore the .pfx to the target managed instance, then restore the database backup.
TDE in SQL Server relies on a certificate (or asymmetric key) that must be present in the target instance to decrypt the database backup. By backing up the certificate and private key to a .pfx file and restoring it to Azure SQL Managed Instance, you ensure the target has the necessary encryption keys to read the backup. Azure SQL Managed Instance supports restoring TDE-protected backups only if the corresponding certificate is first restored into the master database.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Azure Data Studio to import the certificate directly from the local machine store during migration.
Why it's wrong here
Azure Data Studio cannot read a certificate from the Windows local machine store, and SQL Server 2012 certificates must be exported as a .pfx with its password before being uploaded to Azure Key Vault. It is tempting because Azure Data Studio is a legitimate migration tool, but it is used for schema and data movement, not certificate extraction.
- ✗
Disable TDE on the source database, migrate the backup, then enable TDE on the target.
Why it's wrong here
Disabling TDE decrypts the entire 5 TB database, and re-enabling it on the target requires a fresh certificate, so the original encryption is not preserved. It is tempting because disabling TDE before migration is a standard workaround when the source certificate cannot be exported, but that applies only when TDE need not survive the move.
- ✓
Back up the certificate and private key to a .pfx file, restore the .pfx to the target managed instance, then restore the database backup.
Why this is correct
Exporting the TDE certificate and private key to a .pfx, restoring it to the managed instance, then restoring the backup preserves encryption because the instance holds the same protector. This satisfies the stem's requirement to migrate while preserving TDE.
- ✗
Create a master key in the target managed instance and then restore the database; the certificate will be imported automatically.
Why it's wrong here
TDE certificates are not imported automatically; the certificate and private key must be exported from the source and created in the target instance before restore. It tempts because creating a master key is a genuine prerequisite step, but it alone does not preserve TDE.
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
Go deeper
Related to this question
Learn chapter
Overview of Azure Data Platform Options
Key term
Azure SQL Managed Instance
Azure SQL Managed Instance is a fully managed cloud database service that gives you nearly all the features of Microsoft SQL Server on your own server, without you having to manage the hardware or operating system.
Key term
Transparent Data Encryption
Transparent Data Encryption is a security feature that automatically encrypts data written to a database and decrypts it when read, without requiring any changes to the application.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DP-300 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DP-300 exam.