NTP (Network Time Protocol) setup/troubleshooting

Objective:  NTP is used for timesyncing purposes. The clients/servers can get their time synched (to match accuracy) by contacting the NTP server via the NTP protocol.

 Pre-cautions:

• Date & Time on the system plays a major role for the application/database.
• Any abrupt change in the date/time/timezone would adversely affect the application/database running.
• If the difference in the time(between actual & std. time) is more (mnts/hrs); then it is recommended that we take application downtime, before we proceed with system time change or time sync.

Pre-checks:

•   Check if the ‘ntpd’ daemon/process is running:   ‘ps –ef|grep ntp’   ‘lssrc –s xntpd’
•   Check the ‘/etc/ntp.conf’ for the ntp servers.
•  ‘date’ reports date/time/timezone.
•  Simple script to verify the time difference between two servers: 
• “while true; do date; done”   [ctrl-c to terminate script] 
  

Installation Instructions:

• Take the backup of /etc/ntp.conf file.
• Stop xntp daemon. “stopsrc –s xntpd”
• Specify ntp server(of the account) in the ntp.conf file with the ‘server’ keyword.

“cat /etc/ntp.conf|grep -v ^#”

# cat /etc/ntp.conf|grep -v ^#

driftfile /etc/ntp.drift

tracefile /etc/ntp.trace

logfile /etc/ntp.log

server 9.17.129.13               # b03edcore001.ahe.boulder.ibm.com [ntp server]

broadcastclient

#

• Perform time sync using “ntpdate –v ntpserver”
• Start the xtnp daemon. “startsrc –s xntpd”; verify the status “lssrc –s xntpd”
• Look in the /etc/ntp.log for synch status.
• Verify the time difference, looking at two different server windows(putty)
• “while true; do date; done”   [ctrl-c to terminate script]
• If the server is behind firewall, ensure the ‘123’ ntp port is enabled between the server and ntp server.

# cat /etc/services|grep ^ntp

ntp                             123/tcp         # Network Time Protocol

ntp                             123/udp         # Network Time Protocol

# 

Verification / Postchecks:

• Look in the /etc/ntp.log for synch status.
• Verify the time difference, looking at two different server windows(putty)
• “while true; do date; done”   [ctrl-c to terminate script]

 Backout:

Restore the previous ntp.conf and restart ntp daemon.