Copy the ISO file into the VM (i.e. Downloads folder) and create a dir to use to mount the ISO to:
mkdir -p /var/OSimage/OL6.9_x86_64

Mount the directory with ISO file to a path:
mount -o loop, ro /home/oracle/Downloads/CentOS-6.9-x86_64-bin-DVD1.iso /var/OSimage/OL6.9_x86_64/

Go to cd /etc/yum.repos.d and edit the “CentOS-Base.repo” file and add enabled=0 to each section to disable these entries

Add a new file “OL69.repo”

name=CentOS 6.9 x86_64

*Make sure the gpgkey file exists in that path or use an equivalent

Command to check which packages have been installed or not:

rpm -q binutils compat-libcap1 compat-libstdc++-33 gcc glibc glibc-devel ksh libgcc libstdc++ libstdc++-devel libaio libaio-devel libXext libXtst libX11
libXau libxcb libXi make sysstat

Source: Oracle Database Preinstallation Tasks