Real Time Servers Flashcards
NTP
Network Time Protocol
Stratum 0
High-precision reference systems. Atomic, GPS, Radio
Stratum 1
Takes requests for current time from lower level, uses resources to hold time.
Stratum 2
Sanity checking by synchronization
ntpd
Network Time Protocol Daemon. Checks upstream time servers for correct time.
ntpdate
Query specified NTP server, receives time. Do not run ntpd during use.
/etc/ntpd.conf
Configuration file for daemon.
Lines beginning with server indicate contact servers and options. Multiple listed for multiple options.
ntpq
query ntpd daemon for information
- p: peer server
- a: IP address
timedatectl
State of system configuration with NTP server can be checked.
set-ntp: sets up check.
chronyd
Modern NTP daemon for systemd systems.
/etc/chrony/chrony.conf
Config file similar to ntpd.conf pool of servers.
chronyc
Query chronyd on upstream NTP server activity. Enters application. In application: activity: summarizes sources activity. sources: lists all sources. quit: quits application.