I am about to take Oracle Net8 Admin test but am confused about one thing. I was wondering if there a way I could clear the confusion and cement the difference in my mind between PING and TNSPING. I am having a hard time telling the difference. Can anyone tell me how I can separate the two and be able to answer questions on that difference?
All machines on an IP network have an address. When you PING an address (192.168.0.1) you're seeing if something (anything) is on the other end. When you ping a named machine (ie www.oracle.com,www.demon.net etc) you are seeing if a: that name resolves to an IP address (via DNS) and b: if the resolved address exists and c: if the machine at that address has been allowed to reply to a ping.
TNS is essentially the way Oracle a: names an instance and b: resolves the name to an IP or named machined as above. On your machine there should be a file called TNSNAMES.ORA which tells Oracle "when I talk about connecting to an instance named FRED - you can find it on this IP address or named machine".
Ie, if you cannot PING a MACHINE (ip or named) you definately cannot TNSPING an instance which resides on the same machine with the same method of resolution (ip or name).
If you can PING a machine (ip or named), it doesn't necessarily mean you can TNSPING the machine because the TNS entries of what machine it is on aren't necessarily configured.