HP-UX Internet Services Administrator's Guide (August 2003)

Configuring NTP
Troubleshooting NTP
Chapter 496
NTP statistics file (if configured)
The /var/adm/syslog/syslog.log file (xntpd/NTP entries)
The /usr/sbin/ntpq -p output
The ntpdate -d server output (stop the local xntpd first).