Farewell to the Internet’s Master Timekeeper: David Mills

Dr. David L. Mills, the visionary behind the Network Time Protocol (NTP) that synchronizes time across billions of devices globally, died at age 85 on Jan. 17, 2024.

The Chicago song goes, “Does anyone really know what time it is? Does anybody really care?” The answer to both questions for the internet was Dr. David L. Mills.

While not as well known as Jon Postel, one of the internet protocols inventors, and Vint Cerf, co-creator of TCP/IP, Mills’s work on the Network Time Protocol (NTP) was, and is, essential for running the internet. As Cerf wrote, announcing the news of his passing, “He was such an iconic element of the early Internet. Network Time Protocol, the Fuzzball routers of the early NSFNET, INARG taskforce lead, COMSAT Labs and University of Delaware and so much more.”

Today, only network engineers pay close attention to NTP. We don’t think about how hard it is to synchronize time around the world to within milliseconds. But everything, and I mean everything, depends on NTP’s accuracy. It’s not just the internet, it’s financial markets, power grids, GPS, cryptography, and far, far more. NTP syncs up literally billions of devices every moment of every day.

Mills’ journey into the realm of time synchronization began in the 1970s during his time at COMSAT and his involvement with ARPANET, the internet’s precursor. His efforts led to the development of a system that could align computers within milliseconds of each other. Today, NTP is indispensable, operating on devices worldwide and ensuring coordinated timekeeping across continents.

David Mills’ NTP syncs up literally billions of devices every moment of every day.

I met him several times in the early 80s, and he was, in a word, impressive. He didn’t suffer fools gladly, as those who gave him grief about how he maintained NTP, discovered. But, without his efforts, the modern internet wouldn’t exist.

The primary timekeepers of the net are stratum-0 devices, i.e., atomic clocks. These are connected to other devices with NTP, which in turn set the time for everything online.

While the stratum devices belong to government agencies and corporations, NTP itself is a free, open source project that’s overseen today by the Network Time Foundation It has only one manager, Harlan Stenn, Mills’ handpicked successor, and, until recently, he was running NTP on a shoestring from his home. Even now, the Foundation must ask for funds to keep the light on and the time in sync.

While we honor Mills most for his creation of NTP in 1985, his Fuzzball router software was the basis for the first internet routers. Without them, there would be no internet. He also had his hand in the creation of file transfer protocol (ftp) and ping.

As the years went by. Mills lost his life-long battle with glaucoma. This eventually led to blindness. To the end of his life, he kept working on NTP. While, as he said, “I’m considered a bit of an old fogey,” to the NTP community, that didn’t stop him from keeping his hand in.

His achievements have been widely recognized, earning him accolades, such as the Fellow of the Association for Computing Machinery (ACM) in 1999 and the Institute of Electrical and Electronics Engineers (IEEE) in 2002. In 2013, he received the IEEE Internet Award for contributing to network protocols and timekeeping.

There’s a famous xkcd cartoon about how all modern digital infrastructure depends on a single developer in Nebraska thanklessly maintaining it. For many years that was Mills and NTP. We owe him a debt of gratitude. We can thank him by supporting the Network Time Foundation.

Steven J. Vaughan-Nichols, aka sjvn, has been writing about technology and the business of technology since CP/M-80 was the cutting-edge PC operating system, 300bps was a fast internet connection, WordStar was the state-of-the-art word processor, and we liked it.

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