This is just a short reminder for me and a note for you: having recently remastered a CentOS, this one-liner might be helpful to properly create the small bootable ISO.
genisoimage -o $(date +'%H%M').iso -b isolinux/isolinux.bin \
-c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table ./