What protocol is used to ensure accurate time synchronization across network devices?

Network Time Protocol (NTP) is specifically designed for the purpose of synchronizing clocks across various devices on a network. It allows devices to maintain accurate time by synchronizing their clocks with a time server, which may itself be synchronized to a reliable time source, such as an atomic clock. This is critical in many environments, particularly in enterprise networks, where accurate timekeeping can impact logging, scheduling tasks, and maintaining the integrity of transactions.

NTP operates over UDP (User Datagram Protocol) and is capable of providing time accuracy in the milliseconds range over local networks and can extend up to several seconds over the internet, depending on conditions.

The other protocols listed serve different purposes: Simple Mail Transfer Protocol (SMTP) is used for sending emails, Domain Name System (DNS) translates domain names to IP addresses, and File Transfer Protocol (FTP) is used for transferring files between devices. None of these protocols contribute to time synchronization, which is the primary function of NTP.