Azure SQL Database ledger is a critical part of data solutions, providing tamper-evident capabilities to protect the historical data within the database against harmful threats or unauthorized changes. Administrators play a central role in implementing and managing this feature, a key point discussed in the DP-300 Administering Microsoft Azure SQL Solutions exam. In this article, we explore the process of implementing the Azure SQL Database ledger in your systems.
The Crucial Role of Azure SQL Database Ledger
The Azure SQL Database ledger feature enables you to maintain a secure and tamper-evident ledger of any activities in your database, ensuring the highest level of trust and confidence in the data. This feature allows for improved security and transparency, and can help organizations meet various compliance requirements.
The ledger feature uses cryptography to produce cryptographic proofs of the data that can be used to guarantee to auditors, regulators, or other interested parties that the data has not been tampered with.
How To Implement Azure SQL Database Ledger
To enable ledger functionality on an Azure SQL Database, follow these steps:
- Create a new database or choose an existing one: Determine whether you want to apply ledger to a new database or an existing one.
CREATE DATABASE LedgerDB
- Use SYSTEM_VERSIONING: Enable system versioning to keep a record of the data changes in your database.
ALTER TABLE dbo.YourTable
SET (SYSTEM_VERSIONING = ON (HISTORY_TABLE = dbo.YourTableHistory))
- Enable ledger: Enable ledger on selected tables to record changes and actions.
ALTER TABLE dbo.YourTable
SET (LEDGER = ON) ;
Monitoring Azure SQL Database Ledger
Once the Azure SQL Database ledger is enabled on the selected database, it automatically captures all operations that modify the data in the ledger-enabled tables.
Comparison With Traditional Logging
Compared to traditional logging, Azure SQL Database ledger provides more sophisticated and secure logging. The table below shows a brief comparison:
| Feature | Traditional Logging | Azure SQL Database Ledger |
|---|---|---|
| Data accuracy | Depends on logging settings | Cryptographic assurance of accuracy |
| Data integrity | May be compromised in case of system vulnerabilities | High data integrity ensured by cryptographic proofs |
| Tamper-resistance | Low | High, thanks to cryptography |
| Accessibility | Depends on the system configurations and user’s access permissions | Accessible to all users with necessary permissions |
Conclusion
In summary, the Azure SQL Database ledger aids in maintaining and regulating the integrity and security of your database. Administering and maintaining this ledger is a key part of the DP-300 Administering Microsoft Azure SQL Solutions exam. By mastering this feature, you can ensure the credibility of your data, protecting it from unauthorized access or tampering.
Practice Test
True or False: Azure SQL Database ledger is a service that provides cryptographic verification for your data.
• True
• False
Answer: True
Explanation: Azure SQL Database ledger is a service that provides tamper-evidence for your data by creating a cryptographic hash of inserted, updated, or deleted data.
Which of these features is NOT a part of the Azure SQL Database ledger?
• a) Ensuring data tampering evidence
• b) Introducing cryptographic verifiability
• c) Automatically creating and managing databases
• d) Verification of the SQL database state at any point in time
Answer: c) Automatically creating and managing databases
Explanation: While Azure SQL Database ledger enhances data security, it doesn’t automate database creation and management.
In the Azure SQL Database ledger, where are the cryptographic hashes of data stored?
• a) User Database
• b) System Database
• c) Hash Table
• d) Ledger Digest
Answer: d) Ledger Digest
Explanation: The Ledger Digest is a system-produced database where cryptographic hashes of all entries are stored and maintained.
The communication between Azure SQL Database ledger and Ledger Digest is secured using which of these methods?
• a) SSL
• b) Always Encrypted
• c) Data masking
• d) TDE
Answer: a) SSL
Explanation: Azure SQL Database ledger uses SSL to secure the connection and the data exchanged between it and the Ledger Digest.
True or False: Azure SQL Database allows you to export a Ledger Digest.
• True
• False
Answer: True
Explanation: Azure SQL Database ledger allows you to export the Ledger Digest as a way to maintain an offline copy. It solidifies the trust that Azure SQL Database has not tampered with your data.
True or False: Azure SQL Database ledger supports higher isolation levels.
• True
• False
Answer: False
Explanation: Azure SQL Database ledger doesn’t support Serializable or Snapshot isolation levels.
Which version of Azure SQL Database offers ledger functionality without any additional cost?
• a) Standard
• b) Premium
• c) Business Critical
• d) General Purpose
Answer: c) Business Critical
Explanation: Only the Business Critical version of Azure SQL Database offers ledger functionality without any additional cost.
Data from Azure SQL Database ledger can be exported to which of the following services for monitoring and alerting?
• a) Azure Monitor
• b) Azure Storage
• c) Azure DevOps
• d) Azure Security Center
Answer: a) Azure Monitor
Explanation: Data from Azure SQL Database ledger can be exported to Azure Monitor for monitoring and alerting.
True or False: It is mandatory to enable Always Encrypted for Azure SQL Database ledger.
• True
• False
Answer: False
Explanation: It is not mandatory to enable Always Encrypted for Azure SQL Database ledger, but it is recommended for added security.
Which operation is not supported by Azure SQL Database when ledger functionality is enabled?
• a) Insert
• b) Update
• c) Delete
• d) Bulk copy
Answer: d) Bulk copy
Explanation: Bulk copy operations are not supported by Azure SQL Database when ledger functionality is enabled.
Interview Questions
What is Azure SQL Database ledger?
Azure SQL Database ledger is a tamper-evident feature that provides cryptographic verification for your data and helps protect it from unauthorized or unexpected changes.
What does the Azure SQL Database ledger use to secure data?
It uses cryptographic hash functions to protect and secure the data, providing a chain of evidence to validate data.
What is the use of the System-versioned temporal table in Azure SQL Database Ledger?
The System-versioned temporal table in Azure SQL Database Ledger keeps a full history of data changes while assisting with data auditing.
How does Ledger Digest help in data verification?
Ledger Digest provides a tamper-evident log that can be used to detect and prove data tampering, and helps in validating the integrity of the ledger data.
How to enable Azure SQL Database ledger?
To enable Azure SQL Database ledger, apply the “WITH (LEDGER=ON)” clause to the CREATE or ALTER statement of the database.
How could a user verify data integrity in Azure SQL Database ledger?
Azure SQL Database ledger provides the functionality to verify the integrity of ledger data by using the sys.fn_ledger_verify function.
Is it possible to alter the data once Azure SQL Database Ledger has been enabled?
No, once Azure SQL Database Ledger has been enabled on a table, the row cannot be deleted or updated, ensuring the data integrity.
What is the role of the Ledger Digester Service?
The Ledger Digester Service periodically creates cryptographic hashes of the data in the ledger-enabled table and saves them in the Ledger Digest table.
Is there a cost associated with enabling Azure SQL Database ledger?
Yes, enabling Azure SQL Database ledger incurs additional cost as it is considered an advanced security feature.
What happens if data in a ledger-enabled table is tampered with?
If data is tampered with, the digest in the Ledger Digest table won’t match with the result of sys.fn_ledger_verify function. This alerts users to possible data corruption or tampering.
Can Ledgers be enabled on an existing table without data loss?
Yes, ledgers can be enabled on an existing table without loss of data. The existing data will become the first verifiable data state in the ledger control history.
What is the root of trust in Azure SQL Database ledger?
The root of trust in Azure SQL Database ledger is the Ledger Control table. It records control history to establish a cryptographic chain of evidence.
Can the ledger function be disabled once enabled on Azure SQL Database?
No, once ledger is enabled on Azure SQL Database, it cannot be disabled. This is to ensure the integrity and security of the data.
Can ledger-enabled tables be exported?
Yes, the data in ledger-enabled tables can be exported, and can be verified independently of Azure SQL Database.
How are ledger-enabled tables different from non-ledger enabled tables in Azure SQL databases?
Ledger-enabled tables maintain an immutable system-versioned history of all the data changes, which doesn’t happen in non-ledger enabled tables. This provides an additional level of security and data integrity.
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