Maintaining the NetWare server

Time sources

To synchronize, time servers poll at least one other time source:

Single Reference servers are always synchronized and therefore do not poll time sources.
Reference servers must poll another time source, preferably a Primary server, although it can be another Reference server. Although Reference servers do not adjust their time, they must be able to contact another time source before they can claim to be synchronized.
Primary servers must poll either another Primary server or a Reference server.
Secondary servers must poll a Reference, Primary, or Single Reference server to obtain the correct time.

During each polling interval, a time server contacts one, and only one, valid time source. While polling, a server has to find a time source of the right type which matches the server's selection criteria for valid time sources. Although you can allow all time servers of the right type to be valid time sources (any primary server to be a valid time source for any other primary or reference server), you can designate with which sources the server synchronizes.

You can configure a server to recognize any of the following as valid time sources:

The first server in a list that responds to a time synchronization query. The server contacts the time sources in the order listed until one responds. This method works well on a large internetwork because it allows you to turn off the advertising of time services. However, this method requires additional configuration when servers are added or deleted from the internetwork.
The first server in a list that responds to a time synchronization query or, if no server in the list responds, the first server that responds to a general time synchronization query to the network. This method allows you to have preferred servers for time synchronization, and it also allows you to use advertising when all the servers in the list are unavailable. You can restrict the server's contacts with advertising servers to a particular Directory tree or allow any server on the network, regardless of tree, to be a valid time source.
The first server that responds to a time synchronization query to the network. This method does not use a list and relies entirely on the advertising of time services to find a valid time source. This is the quickest and easiest method to set up and allows new servers automatically to fit into the time synchronization configuration. You can restrict the server's contacts to a particular Directory tree or allow any source on the network, regardless of tree, to be a valid time source.

In most circumstances, you can rely on the time synchronization advertising, and you do not need to create a list of sources. However, in the following situations, you may need a custom configuration:

You have more than one Reference or more than one Primary time server on your network and your server is not synchronizing within its Directory tree.
You want to control the sources your server uses for time synchronization.
You want to reduce SAP traffic by turning off time service advertising.

For more information on restricting valid time sources, see the following variables in NetWare Setup:

Enable Time Service Advertising?
Use Only Configured Sources?
Time Sources
Directory Tree Mode

See ``Creating a custom time source configuration'' for more information.