Transport Layer Security protects MongoDB network communications while data travels between clients and servers and, when configured, between MongoDB deployment members. Its core purpose is therefore encryption of data in transit. TLS helps prevent passive interception and tampering and also supports certificate-based identity validation. It is separate from encryption at rest, which protects files on storage media, and separate from Queryable Encryption or client-side field encryption, which protects selected application data before it reaches the server. Option A is unrelated: backup and restore operations use snapshot, managed backup, or database-tool mechanisms. Option B describes the objective of replication, elections, and redundant deployment architecture, not TLS. Option C is also incorrect; TLS is a security control, not a query-optimization mechanism, and cryptographic processing can add some overhead rather than improving query execution. A secure MongoDB deployment normally combines TLS with strong authentication, least-privilege authorization, appropriate network exposure controls, auditing, and storage or field-level encryption as required. For the specific question, enabling TLS provides encryption for data moving across the network, making option D correct.
Study Guide reference/topic:Security, Networking, and Encryption - TLS/SSL, transport encryption, certificates, and network security.
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