Which of the following features is NOT a characteristic of Encapsulating Security Payload (ESP)?

Encapsulating Security Payload (ESP) is a protocol designed to provide various security services in the context of IPsec. Among its primary features are data encryption, integrity, and authentication.

The characteristic of allowing direct memory access does not relate to the function of ESP. Direct memory access (DMA) is a feature typically associated with hardware operations, allowing devices to access the main system memory directly without intervention from the CPU, which is unrelated to the security features provided by ESP. Therefore, option D is the correct choice as it does not align with the security objectives that ESP aims to fulfill.

In contrast, the other characteristics—providing integrity, offering authentication, and encrypting data—are all key components of ESP. Integrity ensures that the data has not been altered during transmission; authentication verifies the source of the data to prevent spoofing; and data encryption protects the content from being read by unauthorized parties, making these features integral to the protocol's purpose in securing network communications.