What is SID and TNSN names.ora in Oracle

SID stands for System Identifier and which is unique for each database ,to which we are connecting and also unique in the TNS.ora File.

TNS Stands for Transparent Network Substrate. via wchich system connects to the database. It hepls to distribute the communication media between the databases. It's the tnsnames.ora which governs the TNS.

TNS File contails the following Information:

1. TCP( Transmission Control Protocol)
2.  Port Number ( 1521: Mostly used by the oracle)
3. HOST IP Address ( where the database gets  resided)
4. SID
5. SERVER NAME.

TNS is  used whenever there are hetergenous colection of protocol in the network.

 The locaton of the .ora file is .....\oracle...\Network\admin

The Parameters like SDU( The session data unit) and TDU(Transport Data Unit) are located in the tnsname.ora file.  SDU defines the size of the packet can be send in the network but not from the Maximum Transmission Unit(MTU). Therefore it is always recommend that SDU shoud be set equal to the size of the MTU because we don't want to waste network resources by transport wasted spaces in each packet.

All the below neccesary things need to be configure in the tnsnames.ora file to connect the system with the database.



The tnsnnames.ora file is located in both client and server systems. And need to configure in both the sides.



Thanks.....Have Fun..