Glossary A–ZLetter T
Time synchronisation (NTP)
Time synchronisation is the automatic adjustment of a device’s clock to an accurate time source on the network; this is usually done via NTP, the Network Time Protocol.
The device regularly queries a time server and corrects its clock.
Every piece of time-controlled content depends on the player’s clock: the breakfast offer in the morning, the switch-off time in the evening, the start of a campaign at midnight. Synchronised playback across several screens needs a particularly accurate shared time. Logs and proof-of-play records are also only as good as their timestamps.
NTP supplies Coordinated Universal Time (UTC); local time only results from the configured time zone. Firewalls must allow access to the time server, for which NTP uses UDP port 123, or a dedicated time server must be provided on the company network. Devices without a battery-backed clock start with the wrong time after a power cut until the first synchronisation succeeds; with a wrong clock, encrypted connections fail too. A power-cut test is therefore part of initial setup.