what is the difference between yum and dnf
DNF (software) DNF or Dandified YUM[2][3][4] is the next-generation version of the Yellowdog Updater, Modified (yum), a package manager for .rpm-based distributions. DNF was introduced in Fedora 18,[5] and it has been the default package manager for Fedora since version 22.[6]
Domain Name System The Domain Name System (DNS) is a hierarchical decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates more readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. By providing a worldwide, distributed directory service, the Domain Name System is an essential component of the functionality on the Internet, that has been in use since 1985.