DNF or Dandified Yum is the next generation version of the Yellowdog Updater, Modified (yum), a package manager for RPM-based distributions. DNF was introduced in Fedora 18,[2] and it has been the default package manager for Fedora since version 22.[3] Perceived deficiencies of yum which DNF is intended to address include poor performance, high memory usage, and the slowness of its iterative dependency resolution.[4] DNF uses libsolv, an external dependency resolver.[4]