All current versions of ISC-hosted software, including BIND 9.11.0b and greater, Kea DHCP 1.0.0 and greater, and ISC DHCP 4.4.0 and greater, are available for free under the Mozilla Public License 2.0.
Mozilla publishes a helpful FAQ about the MPL 2.0 license.
The MPL 2.0 license is approved by the Open Source Initiative.
BIND 9 versions prior to BIND 9.11.0b, ISC DHCP versions prior to ISC DHCP 4.4.0, and Kea versions prior to Kea 1.0.0 were released under the ISC License, the text of which is shown below. The ISC License is registered with and approved by the Open Source Initiative.
Text of the ISC License:
Copyright © 2004-2013 by Internet Systems Consortium, Inc. (“ISC”)
Copyright © 1995-2003 by Internet Software Consortium
Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED “AS IS” AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.