Links

Links between tables produce an effect similar to paths, except that the link involves a search through only one table: the remote table. With a search path, NIS+ first searches the local table, and only if it is unsuccessful does it search the remote table. With a link, the search moves directly to the remote table. In fact, the remote table virtually replaces the local table. The benefit of a link is that it allows a lower domain to access the information in a higher domain without the need to administer its own table.

To create a link, use the nisln command. You must have modify rights to the table object.

Deciding whether to use a path or to link NIS+ tables in a domain is a complex decision, but here are some basic principles:

• Every domain must have access to every standard table.

• Volatile, frequently accessed data should be located lower in the hierarchy. Such data should be located closer to where it is used most often.

• Data that is accessed by several domains should be located higher in the hierarchy, unless the domains need to be independent.

• The lower in the hierarchy you place data, the easier it is to administer autonomously.

• Only NIS+ clients can see tables connected by paths and links. They cannot be seen by NIS clients, as illustrated by the following figure:

Figure 26–9 Information Distribution Across an NIS+ Hierarchy