Which of the following is a protocol that enables serverless backup?

SMTP (Simple Mail Transfer Protocol) is used for sending and receiving email messages, not for serverless data backup.

SNMP (Simple Network Management Protocol) is used for monitoring and managing network devices, not for serverless data backup.

NDMP (Network Data Management Protocol) facilitates serverless backups by enabling direct data transfer between Network Attached Storage (NAS) devices and backup devices (like tape libraries) without data having to pass through a backup server. This offloads the backup server from the data path, improving performance and reducing network load.

SMPTE (Society of Motion Picture and Television Engineers) is an organization that sets standards for motion picture and television, not a data backup protocol.