You work as a Database Administrator (DBA) for a company named ABC.com. The company has a Windows Azure subscription. The company uses a cloud based SQL Server environment hosted on SQL Azure…

SSL (Secure Sockets Layer) encrypts data in transit between client and server but does not protect data at rest stored in the database.

IPSec is a network-layer protocol that secures communication between network nodes in transit and does not provide encryption for data stored within a database.

Data encryption (column-level or application-level encryption) is the most suitable solution for securing specific sensitive fields like usernames, passwords, and credit card numbers within a database. It allows targeted encryption of individual columns containing sensitive data, ensuring that even users with database access cannot read the plaintext values of protected fields. This approach directly addresses the requirement to securely store and reuse specific sensitive data elements at rest within SQL Azure.

Transparent Data Encryption (TDE) encrypts the entire database at the file/storage level, protecting physical media, but does not encrypt individual columns so authorized database users can still read sensitive values like passwords and credit card numbers in plaintext.

Encrypting File System (EFS) is a Windows file-system-level encryption feature that protects files on disk and is not applicable to encrypting specific data values stored within a SQL Azure database.