RHEL7 Disable IPv6

This has changed significantly from RHEL 6

Here ae the steps:

GRUB_CMDLINE_LINUX=“rd.lvm.lv=rhel/swap crashkernel=auto rd.lvm.lv=rhel/root ipv6.disable=1”

* Run the grub2-mkconfig command to regenerate the grub.cfg file:
# grub2-mkconfig -o /boot/grub2/grub.cfg

Alternatively, on UEFI systems, run the following:     
# grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

See the link at https://access.redhat.com/solutions/8709