Since it may be a while before I'm ready to use the IPv6 on my systems, I've been disabling IPv6 on most servers so far. And since there's a particularly elegant way of doing this in Red Hat Linux, I think it's worth sharing.
How to confirm if IPv6 is running on your system
IPv6 is implemented as a kernel module, so you can use the lsmod command to confirm if it's currently running on your Red Hat system:
$ lsmod | grep ip ipv6 410913 36
If lsmod doesn't return anything, it confirms that your system isn't running IPv6.
Prevent IPv6 from getting started by modprobe
As you probably know, modprobe command is used for probing modules upon system boot. Probing simply means a module is loaded and an attempt is made to start it up. With any luck, the module starts successfully and its functionality becomes available to the Linux kernel.