Selection
Public NTP pool vs local GNSS time server
Office PCs and auditable cabinet timing are different jobs. Firewalls, audit needs, and I/O decide if you need a local GNSS server.
Updated 2026-08-22
Decision
Need auditable on-prem time? Choose a local GNSS server.
Notes
A public NTP pool is fine when devices have reliable Internet egress, millisecond drift is acceptable, and there is no mandate for an on-premises time source.
If the plant or cabinet forbids casual egress, you need an auditable local source, or you also need 1PPS / PULSE / Modbus absolute time, deploy a LAN GNSS NTP server. Need IRIG-B? See SY-4096.
A local server keeps the time reference inside your control boundary: antenna and device can be inspected, and the datasheet can state include/exclude for tenders.
Do not accept cabinet hardware edges against public NTP behavior, and do not accept remote Internet clients against GNSS 1PPS nanosecond figures.
Hospitals: see the 10-step bring-up note and /solutions/hospital-weak-current/. Schools: /solutions/school-campus/ and the school-campus-ntp guide.
SY-1231 targets LAN Stratum 1 in cabinets—download the datasheet and confirm capacity and protocol scope before you buy.
FAQ
- What is the decision?
- Need auditable on-prem time? Choose a local GNSS server.
- What are the key points?
- Office PCs and auditable cabinet timing are different jobs. Firewalls, audit needs, and I/O decide if you need a local GNSS server.