Day 11 of the Linux Mastery series focuses on setting up a local repository using RHEL 9 ISO for systems without internet access.Repositories are essential for installing software packages where dnf install command could fail without knowing where to find the package.Local repositories can be set up offline using RHEL ISO files, which are packed with default software.Core dnf commands include mounting an ISO, creating a mount point, editing .repo files, cleaning cache, and installing packages.A real-world scenario involves mounting the RHEL 9 ISO, creating a .repo file, cleaning and verifying repos, and installing Apache locally.Steps include mounting the ISO, creating .repo files, clearing cache, verifying the new repo, and installing software packages.Setting up a local repository is crucial for Linux system administration in secured environments with no internet access.This skill involves managing ISO files, writing .repo files, and working offline, making it a common task in Red Hat systems.The article guides on mounting, creating .repo files, and installing packages offline, showcasing a repeatable task for Red Hat systems.The process outlined using RHEL ISO enhances the understanding of managing local repositories for software installations.