NTP100 – Rev 2.2.0 Oct-12
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Problem: Device appears to ‘reset’ periodically.
Possible Reasons/solutions:
1. Check the network connection and setup. If DHCP is enabled [Note: DHCP is enabled by default] and a DHCP
server is not active on the local network the clock will hesitate periodically while attempting to resolve DHCP
configuration. To correct the problem, switch to manual networking configuration or determine why the local
DHCP server is not operating.
2. If the device cannot resolve its DHCP address in DHCP mode, the unit will periodically perform a soft restart to re-
initialize its communication port and DHCP configuration. See the trouble shooting section on fallback IP address
3. If the device has not been configured with at least one valid DNS server (or that DNS server is down) hesitations
similar to those described in #1 will occur. At least one valid DNS server is required for operation.
Problem: Unable to communicate with the NTP100 on the network with Telnet
1. If the NTP100 has been configured to use DHCP for network configuration but no DHCP/BOOTP server is present, the
NTP100 may not respond to discovery requests for up to twenty seconds after power-on. [Note: DHCP is enabled as a
factory-default.]
2. Verify that you have the correct IP address for the unit and the IP address did not change. If using DHCP to provide the
IP address, this address may change periodically, you must know the IP address of the unit to use the TELNET interface.
3. Verify that the device does not have the Telnet interface disabled.
[Note: for security purposes, the Telnet interface can be disabled. When disabled, you will no longer be able to access the
unit with Telnet. To re-enable the Telnet feature, one of the other configuration methods must be used, or the unit must be
reset to factory default configuration.]
Problem: NTP/SNTP client application or W32Time service is unable to communicate with the NTP100
1. Verify that the NTP100 is attached to the network.
2. Verify that all network cables, hubs, etc. are in proper working order. Be sure that Ethernet crossover cables are not
being used where inappropriate.
3. Verify that the NTP100 is actually reachable from the client. Try “pinging” the IP address of the NTP100. If this
fails, it is possible that the NTP100 has an invalid network configuration or that the network is down. Consult your
network administrator for assistance.
4. Verify that the NTP100 is set to output if operating in internal oscillator/real time clock mode and that the maximum
time difference has not been exceeded.
5. Verify that the client application or service is not using “Symmetric Active” mode. The NTP100 device does not
use Authentication and will not work with NTP/SNTP clients that are configured for operation in a symmetric active
mode. The client application or service must be configured to use client mode.
Note: By default – The Windows 32Time service for Windows Server 2003 and Windows XP (service pack 2 and
above) is configured to use Symmetric Active mode.
Note: Adjusting the W32Time service involves stopping the service, adjusting /editing registry settings and then
restarting the W32Time service. Recommendations or procedures for adjusting or editing the registry in order to
utilize the W32Time service as a client/server is out of the scope of the support provided by Masterclock.. Please
refer to the appropriate knowledgebase article at the Microsoft support site. . http://support.microsoft.com/
If using the Windows W32Time service, See the appropriate knowledgebase articles at the Microsoft website
regarding using the Windows W32Time service (built in NTP/SNTP time client for the Windows VISTA, Windows
Server 2003, Windows XP and Windows 2000 OS’s ).
The Microsoft support knowledgebase article #875424 entitled: “ Time synchronization may not succeed when you
try to synchronize with a non-Windows NTP server in Windows Server 2003” pertains to addressing the symmetric
active mode issue with Windows 2003 server. http://support.microsoft.com/kb/875424/
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