Você está baixando o ISO incorreto:
Red Hat Enterprise Linux 7.4 Boot ISO
A minimal boot image which can be used to boot the installation program, but requires access to additional package repositories from which software will be installed. Red Hat does not provide such a repository; you must create it using the full installation ISO image.
Você realmente quer o seguinte ISO
Red Hat Enterprise Linux 7.4 Binary DVD
A full installation image which can be used to boot the installation program and perform an entire installation without additional package repositories.