NTP
Network Time Protocol
Provide accurate timing in the network and synchronize routers, hosts, and other network devices.
![](/note/computer-network/application-layer/ntp/NTP_hua7755a23f74aece6fdce52eaa24c39e2_482807_7381ff6a14250fb747cdc49cbe538ba5.png)
Structure
NTP timing service uses a hierarchical architecture organized into 16 stratums
- An NTP primary server, or stratum-1, is synchronized with a high precision clock
- At least 175,000 hosts running NTP in the Internet
Operation Mode
- Clients and servers can operate in the multicast or broadcast mode.
- NTP client synchronize with a server in two ways
- Query time information from and synchronize to a remote NTP server, use rdate or ntpdate
- Synchronize with a remote server continuously and automatically, use ntpd