There are two features of Oracle Names version 8 that optimize the
speed with which client name queries can be resolved:
* client-side daemon process to find the fastest responding Names Server
* client-side cache
Client Cache.
On most platforms, a local client cache is created when a client is started. Once a current list of Names Servers is retrieved, that list is stored in the local client cache. Similarly, when a name query is resolved by a Names Server, the result of that query is stored in the client-side cache. Clients attempt to find the result of a query by first looking in their cache, so that subsequent requests for name resolution can be answered, in most cases, more quickly than a network round trip between client and Names Server. Any names that are not in the local client-side cache, or have timed out, are retrieved by forwarding the query on to the Names Server.
The local client-side cache is particularly advantageous if at some time no Names Server is available. In this case, the local client-side cache has the current list of recently accessed services.All the information in the client cache has a time to live (TTL). At the end of that TTL, the information is flushed from the cache. The purpose of this feature is to avoid having stale information in the client cache. The default TTL is 86,400 seconds (24 hours). It cannot be changed.
Not all platforms support the client-side cache. If the client platform does not have a cache, the result of the initial discovery process is stored in .SDNS.ORA in the client's $ORACLE_HOME/NETWORK/NAMES directory.
See 'Net8 Administrator's Guide'.