I have configured samba4 and ntp following the official HowTO. Client computers running Windows XP synchronize their time correctly but only when windows starts or after a restart (same thing). My ntp.conf is the same found in the HowTo. ntp version is 4.2.6p4 and I set the following domain policy: In Computer Configuration\Administrative Templates\System\Windows Time Service\Time Providers\ - Enabled Windows NTP client - Configuration of NTP clients: NtpServer: mysamba4server,0x01 What it is needed to get these clients synchronize their time without restarting? Best regards, Felix.