Why Encryption & Backup Matter
Data is the most critical enterprise asset. Without proper encryption and backup, organizations risk data breaches, compliance violations, and irreversible loss. Azure provides built-in encryption mechanisms and flexible backup/restore options to ensure data security and recoverability.
1. Encryption in Azure
a. Transparent Data Encryption (TDE)
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Encrypts Azure SQL Database, Managed Instance, and SQL Server on VM at rest.
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Protects backups, logs, and data files.
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Enabled by default in Azure SQL.
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Can use Service-Managed Keys (SMK) or Customer-Managed Keys (CMK) from Key Vault.
b. Always Encrypted (SQL)
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Encrypts sensitive columns (e.g., SSN, credit cards).
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Data stays encrypted in transit and at rest.
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Even DBAs cannot view plaintext values.
c. Azure Key Vault Integration
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Centralized service to manage secrets, keys, and certificates.
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Supports BYOK (Bring Your Own Key).
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Key rotation policies for compliance.
d. Storage Service Encryption (SSE)
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Encrypts Blob, File, Table, and Queue data at rest.
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Default = Microsoft-managed keys.
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Option for CMK with Key Vault.
e. Encryption in Cosmos DB
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Data encrypted at rest by default.
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Supports CMK with Key Vault.
2. Backup & Restore in Azure SQL
a. Automated Backups
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Retention: 7–35 days (default).
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Geo-redundant backups supported.
b. Point-in-Time Restore (PITR)
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Restore database to any point in retention window.
c. Long-Term Retention (LTR)
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Store full backups up to 10 years.
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Useful for compliance (e.g., banking, healthcare).
d. Geo-Restore
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Recover database in another region from geo-redundant backups.
3. Backup & Restore in Cosmos DB
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Continuous Backup: Restore to any point in the last 30 days.
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Periodic Backup: System-managed snapshots.
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Geo-distribution ensures data redundancy.
4. Backup & Restore in Storage
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Blob Snapshots: Point-in-time copies of blobs.
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Blob Versioning: Automatically tracks changes.
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Soft Delete: Protects against accidental deletion.
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Azure Backup Service: Backs up VMs, files, and storage to Recovery Services Vault.
Example Enterprise Scenario
A financial services company requires:
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SQL DB must encrypt all data with customer-managed keys.
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Must retain transaction data backups for 7 years.
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Cosmos DB must support point-in-time restore.
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Blob storage must recover files deleted accidentally.
Correct design:
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Enable TDE with CMK from Key Vault for SQL DB.
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Configure SQL LTR backups for 7 years.
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Use Cosmos DB continuous backup.
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Enable Blob soft delete + versioning.
Confusion Buster
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TDE vs Always Encrypted
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TDE = database-level encryption at rest.
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Always Encrypted = column-level encryption (sensitive fields).
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Service-Managed Keys vs Customer-Managed Keys
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SMK = managed by Microsoft.
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CMK = stored in Key Vault, customer control.
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PITR vs LTR
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PITR = restore to a specific time (short-term).
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LTR = compliance retention (years).
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Blob Snapshot vs Versioning
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Snapshot = manual copy.
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Versioning = automatic change tracking.
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Exam Tips
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“Which feature encrypts SQL DB backups at rest by default?” → TDE.
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“Which SQL feature ensures DBAs cannot view SSNs?” → Always Encrypted.
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“Which option allows customer control over encryption keys?” → Key Vault CMK.
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“Which SQL backup option supports 10-year compliance retention?” → Long-Term Retention.
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“Which Blob feature restores deleted files?” → Soft Delete / Versioning.
What to Expect in the Exam
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Direct Q: “Which service stores and rotates encryption keys for Azure SQL DB?” → Key Vault.
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Scenario Q: “Bank requires 7-year backup retention for compliance.” → SQL LTR.
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Scenario Q: “Healthcare DB must ensure sensitive data is not visible to admins.” → Always Encrypted.
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Scenario Q: “Company needs to restore a deleted Blob.” → Blob soft delete.
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Trick Q: “TDE ensures column-level encryption.” → False (Always Encrypted does).