I have to setup an environment for APEX, with Linux RedHat and ORACLE 11.g, APEX 4.2.What distribution or Oracle are you talking about? Enterprise? SE? XE? If it's XE, then the database only can use 1GB of memory, so that answer is simple. A few years back I was hired to create several custom database applications for a company. They'd never used Oracle so had nothing on site. To minimize their investment while I was bringing the first apps from development to production, I picked up an HP Proliant DL360 G3 from eBay and installed Fedora and 10G XE on it. The server was a dinosaur even then with only a pair of single-core Xeon processors (XE only uses one anyway), and 4GB of RAM. It served as a production server for about a year before I hosted the database on a server from the current millennium. Pretty much any enterprise server you were to purchase now would exceed the specs of that box, so if you're using XE, it should work.