- Checking the network setup:
a.       Verify the hostname (Issue command hostname)
b.      Change the current hostname in kernel
sysctl kernel.hostname=NEW_HOSTNAME
2.      Editing Hostname /etc/hosts
                127.0.0.1      localhost.localdomain localhost
      ::1            localhost6.localdomain6 localhost6
      192.168.x.x   fullhostname       hostname
3.      All necessary prerequisites will be performed automatically. 
If you plan to use the “oracle-rdbms-server-11gR2-preinstall” package to perform all your prerequisite setup, follow the instructions at https://public-yum.oracle.com to setup the yum repository for OL, then perform the following command. 
        # cd /etc/yum.repos.d
        # mv Oracle-Base.repo Oracle-Base.repo.disabled# wgethttps://public-yum.oracle.com/public-yum-el5.repo
        # yum list  # yum install oracle-rdbms-server-11gR2-preinstall        Or 
        # yum install oracle-validated
4.       Manual Configuration. 
4.1   Add the following lines to the /etc/security/limits.conf file:
oracle soft nproc 2047oracle hard nproc 16384oracle soft nofile 4096oracle hard nofile 65536oracle soft stack 10240
4.2   Edit /etc/selinux/config file and disable SELINUX
                SELINUX=disabled
5         Create the new groups and users:
groupadd -g 501 oinstallgroupadd -g 502 dbagroupadd -g 503 operuseradd –u 502 -g oinstall -G dba oraclepasswd oracle
6         Create the directories in which the Oracle software will be installed:
      mkdir -p /u01/app/oracle
      chown -R oracle.oinstall /u01
7         Login as root and issue the following command:
xhost +
8         Edit /home/oracle/.bash_profile from oracle user as:
export ORACLE_HOSTNAME=hostname;export ORACLE_UNQNAME=orclunq;export ORACLE_BASE=/u01/app/oracle;export ORACLE_HOME=$ORACLE_BASE/product/11.2.0/db_1;export ORACLE_SID=orcl;export PATH==$ORACLE_HOME/bin:$ORACLE_HOME/OPatch:/usr/sbin:$PATH;export LD_LIBRARY_PATH=$ORACLE_HOME/lib:/lib:/usr/lib;export CLASSPATH=$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib;
9         Unzip Installer of Oracle Database
                # unzip oracle_Linux-x86-64_1of2.zip
      # unzip oracle_Linux-x86-64_1of2.zip
10     Start the Oracle Universal Installer (OUI) by issuing the following command in the database  directory:
      # ./runInstaller
11     Fix the RPM issues and Kernel Parameters as suggested
12     Follow the GUI generated by OUI to complete the installation according to requirement.
13     Install Only Software, By choosing Setup Wizard.
14     After installation of software create database with command
      # dbca
14.1.1      While setting Memory Parameter, Check off the Automatic Memory Management Check Box and choose Set SGA/PGA with Needs