Why Encryption Matters
Encryption ensures that even if data is accessed without authorization, it cannot be read.
Azure provides encryption at rest (storage, databases, disks) and encryption in transit (data moving across networks).
Encryption at Rest
Azure automatically encrypts data stored in its services.
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Storage Accounts
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Data encrypted by default using Storage Service Encryption (SSE).
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Supports Microsoft-managed keys (default) or customer-managed keys (CMK) in Azure Key Vault.
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Azure SQL Database & Cosmos DB
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Use Transparent Data Encryption (TDE).
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Ensures database files are encrypted on disk.
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Virtual Machine Disks
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Encrypted with Azure Disk Encryption (ADE).
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Uses BitLocker (Windows) or DM-Crypt (Linux).
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Keys stored in Key Vault.
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Encryption in Transit
Data moving between users, apps, and Azure services is protected via:
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TLS/SSL encryption (HTTPS connections).
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VPN encryption for site-to-site and point-to-site traffic (IPsec/IKE).
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Private Link to keep traffic on the Azure backbone (avoids public internet).
Confusion Buster 🚨
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Encryption at Rest vs In Transit
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Rest = data stored on disk (Storage, DB, Disks).
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Transit = data moving across network (TLS, VPN).
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Microsoft-managed vs Customer-managed keys
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Default = Microsoft manages keys.
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CMK = stored in Key Vault, gives customers more control.
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Exam trap: If the question says “use customer-provided keys for storage encryption”, answer is CMK in Key Vault, not the default SSE.
Simple Example
A financial company:
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Stores documents in a Storage Account with CMK encryption from Key Vault.
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SQL Database is encrypted automatically with TDE.
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VM disks use BitLocker via ADE.
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Client connections to the app are secured using HTTPS/TLS.
Exam Tip
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“Storage encrypted by default” → SSE with Microsoft-managed keys.
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“Control over keys” → Customer-managed keys in Key Vault.
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“Encrypt SQL Database files on disk” → Transparent Data Encryption (TDE).
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“Encrypt VM OS/Data disks” → Azure Disk Encryption.
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“Encrypt traffic between Azure & on-prem” → VPN with IPsec/IKE.
What to Expect in the Exam
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Direct Q: “Which encryption method protects Azure SQL Database at rest?” → Transparent Data Encryption.
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Scenario: “Company requires customer-managed encryption keys for storage.” → CMK via Key Vault.
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Trick Q: “Azure storage is unencrypted by default.” (False — it’s encrypted by default).