if you have correct NTP client configuration, clock works fine in RB500.
Yes, the NTP server works. It is the national NTP server for New Zealand. All our Debian boxes use it. No, it doesn't respond to ping.
[admin@ara-imperial] > /system resource print
uptime: 1w7h32m33s
free-memory: 18936kB
total-memory: 30384kB
cpu: "MIPS 4Kc V0.10"
cpu-frequency: 266MHz
cpu-load: 7
free-hdd-space: 98976kB
total-hdd-space: 126976kB
write-sect-since-reboot: 0
write-sect-total: 0
[admin@ara-imperial] > /system ntp client print
enabled: yes
mode: unicast
primary-ntp: 131.203.16.6
secondary-ntp: 0.0.0.0
status: started
[admin@ara-imperial] > /system clock print
time: 07:32:03
date: jan/08/2000
time-zone: +12:00
[admin@ara-imperial] >