Network Time Service

What is NTP?

The Network Group provides three NTP (Network Time Protocol) servers for campus-connected machines. NTP servers allow workstations to determine the correct date and time with a high degree of accuracy. Tihs is often necessary for precision control of file systems, including the distributed Andrew File System (AFS). We will also respond to UDP time requests sent by client machines.

Stratum Two Service

We provide stratum-two and stratum-three servers for user queries. Each stratum represents one more level of indirection from a highly accurate (atomic or GPS) clock; a stratum two server communications with a machine directly connected to a high accuracy clock, while a stratum three server communicates with multiple other NTP servers to ensure accurate time information. Our stratum-two servers communicate with an on-campus GPS clock as well as several off-campus stratum-one servers.

Our Servers

We recommend client machines contact one of our stratum-two or stratum-three servers rather than directly contacting a stratum-one server. This reduces the load on such servers. Our servers are open for off-campus queries as well.

Server Hostname	Stratum
ac-ntp0.net.cmu.edu	Two
ac-ntp1.net.cmu.edu	Two
ac-ntp2.net.cmu.edu	Two