How To Flush Linux / UNIX DNS Cache last updated June 2, 2012 in Categories BASH Shell, CentOS, Debian / Ubuntu, FreeBSD, Linux, Networking, RedHat and Friends, Troubleshooting, Ubuntu Linux, UNIXI‘m on a Dial UP Internet connection under Linux and frequent dial up disconnection causing dns problems. How do I flush DNS cache under UNIX / Linux distribution using a shell prompt?