The Domain Time II Control Panel Applet - Broadcast Time Tab

Domain Time II Control Broadcasts

This section allows you to set whether the Server will send these control messages to its slaves and clients. Caution: Modifying these entries can have a significant effect on the overall accuracy of your network time. Modify them with care.

Enable Cascade Signals
When this checkbox is checked, Server will send Cascade triggers to its slaves and/or clients. Cascade triggers inform the recipient that they must synchronize with their time source immediately, and if they have slaves or clients of their own, to instruct them to synchronize immediately as well.

Enable Advisory Signals
When this checkbox is checked, Server will send Advisory messages to its slaves and/or clients. Advisory messages inform the recipient that the server has recently synchronized its time and that the component should synchronize its time as soon as possible.

Warning:

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You should never have more than one time server (whether Domain Time II or a third-party product) providing time broadcasts on the same network! Severe adverse consequences to your network's time can result, including the potential for clock reversals. Although you can configure Domain Time clients to prevent them from responding to rogue broadcasts, other clients may be severly confused by multiple broadcasts.

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Domain Time II Heartbeats

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Enable Heartbeats
When this checkbox is checked, Server will send Heartbeats of the type you select using the radio buttons, on the schedule you specify using the selection boxes.
Advisory only (2.5 compatible)
For Domain Time components version 2.5 and later. When a Client receives a Domain Time II Heartbeat pulse, it will immediately attempt to synchronize with its server (which is not necessarily the machine providing the pulse). The main advantage to this method is that a Client can never use an incorrect time source as a result of the broadcast. The disadvantage is that it is less efficient than broadcasts that include time information since the client is required to request a time update from its source.

Send time information
Domain Time Version 3.1 and later. Time sync data is included in the Heartbeat broadcast packet itself, and a Client will immediately set its time to match the packet. This results in significantly lower overhead than the Advisory Only Heartbeat. This is the ideal selection to use with the Ultra Thin Client.

The only potential disadvantage to this method is that an unconfigured client could potentially respond to conflicting broadcasts from other broadcasting servers. However, Domain Time Clients can be configured to only accept time broadcasts from specified servers to prevent this issue.

Set the schedule to the maximum period that provides the accuracy you require. Setting the broadcast to occur too often can actually degrade accuracy by creating too much network traffic and system overhead.

NTP Time Broadcasts

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Enable NTP Time Broadcasts
When this checkbox is checked, Server will send NTP Broadcasts on the schedule you specify using the selection boxes.
Use NTP Broadcasts only if you have third-party clients on the network that require them. The NTP Broadcast Version drop-down box lets you select the version of NTP Broadcast to be sent (for compatilibity with various clients). Choose the version your client(s) require.

Set the schedule to the maximum period that provides the accuracy you desire. Setting the broadcast to occur too often can actually degrade accuracy by creating too much network traffic and system overhead.

Important:

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Domain Time II Server's ability to serve NTP is disabled by default when Server is installed on a Windows Active Directory Domain Controller. On those machines, the Windows Time service is set to provide NTP for compatibility with Windows Time clients using the NT5DS sync mode. You will not be able to send NTP Broadcasts from a Active Directory DC unless the NTP server portion of Windows Time service is disabled on that machine. This will require any Windows Time clients on the network to be changed from NT5DS to NTP Client sync mode. See the Co-existing with Windows Time page for a complete explanation.

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• When to use Heartbeats and NTP Broadcasts
• Cascading Time Hierarchy
• More information about time protocols and accuracy
• Working across subnets
• How Domain Time II distributes time
• How to implement Domain Time II on your network