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]
Push-button telephone The international standard for telephone signaling utilizes dual-tone multi-frequency (DTMF) signaling, more commonly known as touch-tone dialing. It replaced the older and slower pulse dial system.[17][18] The push-button format is also used for all cell phones,[12] but with out-of-band signaling of the dialed number.