Tuesday, July 7, 2009

Network Time Protocol (NTP) Notes

Synchronizes the local system and can be configured to synch any NTP-aware host

Hierarchical in design - 1 through 16 strata
Lower stratum values are more accurate time sources
Stratum 1 servers are connected to external, more accurate time sources such as GPS

Note: Less latency usually results in more accurate time

External Time Source(GPS/Radio/etc.)
-NTP - Stratum 1
-NTP Stratum 2 - Solaris Client/Server
Note: A Solaris 10 NTP system can be both client & server

Note: configure NTP clients to synch to 3 or more clocks(time sources)

###Client configuration###
xntpd or the ntp service searches for /etc/inet/ntp.conf

Note: NTP uses UDP 123 in source & destination ports

ntpdate ntp_server - synchronizes, one-off, local clock
Note: ntpdate does NOT update local clock if xntpd is running locally

rdate - relies upon older time service

ntpq - NTP query utility runs interactively & non-interactively
ntpq -np - lists peers without name resolution - non-interactive invocation
ntpq - invokes interactive mode

ntptrace - traces path to time source

ntpq - queries local or remote NTP servers
ntptrace - traces path to external time source
ntpdate - updates local clock
/etc/inet/ntp.conf - (server server_ip)
svcadm enable ntp - starts NTP (Server and/or Client)

NTP Pool Site: www.pool.ntp.org (Derive NTP public servers from their lists)

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