The process of resolving a service name (or database alias or global name) into a server’s physical address is known as name resolution. While the information needed to perform name resolution between service names and specific Oracle instances and hosts is normally maintained in the tnsnames.ora file, that approach requires propagation of modifications to tnsnames.ora across the enterprise whenever there is a change to any component. This may be inconvenient or even impossible in installations where changes occur often or where coordination of tnsnames.ora files is difficult. To solve this problem, Oracle developed a product called Oracle Names, which provides dynamic resolution of service names through the use of an Oracle Names server. By using Oracle Names, a network node only needs to know how to connect to the Oracle Names server, which then resolves any service names without a need for tnsnames.ora. In addition, Oracle Names is able to integrate with many native naming services, such as Network Information Services (NIS), Novell NetWare Directory Services (NDS), and Banyan Vines StreetTalk.

The Oracle Names method for name resolution has a number of positive attributes. This method:

In order to use Oracle Names, one or more Names servers must be configured and implemented using the Oracle Network Manager, described later in this chapter. Once installed, Names servers are server-based services and must be controlled using the program namesctl. This control program, which is similar to the lsnrctl control program for the SQL*Net listener, performs routine tasks such as starting and stopping the Names server, obtaining status information, and maintaining the name cache.