You can’t “yum install -y dig” to install dig because dig is not a package. The package that provides dig, nslookup and host commands is bind-utils.
Have you ever needed to install these commands? Probably not unless you have a minimal install where even some basic tools are missing. This is great because it forces you to learn.
Which package provides dig?
Files/commands provided by bind-utils
rpm -ql bind-utils