Software Support Policy

Our current policy is that software releases are supported until two major releases, (major releases are based upon significant new features to the code) have come out after them. Examples of major releases are BIND 9.9 and 9.10, or DHCP 4.1 and 4.3. For example: 9.7.x general support was phased out 6 months after 9.9.0 was introduced. Currently, we publish minor, or maintenance releases approximately every six months and major releases approximately every 2 years. We will support no more than four major releases of either BIND or DHCP, in total, at any one time.

ESV Releases

ISC first introduced its ESV (Extended Support Version) in the summer of 2009 for users who have longer upgrade cycles.  Each ESV will be supported for at least four years from the initial release of that major version.

Beginning with BIND 9.9 Extended Support Version we changed our version naming practices for ESV releases. In prior ESV sequences (e.g. 9.6-ESV), when the series was designated an extended support version, the name of the release versions was changed to include the indicator “ESV” instead of a minor version number. The BIND 9.9 series will instead continue the 9.9.x naming convention, adding “(Extended Support Version)” to indicate the ESV status.

The first version of BIND 9.9 to be designated ESV is BIND 9.9.3 (Extended Support Version). Subsequent versions will be supported according to the commitment for extended support version but will receive version names that follow our normal sequence (i.e. the version which follows 9.9.3 (Extended Support Version) will be called 9.9.4 (Extended Support Version) if it is a regularly scheduled maintenance release, or will be called 9.9.3-P1 (Extended Support Version) if it is an out-of-cycle security patch update to 9.9.3.)

Here are our current ESV versions and their EOL dates:


  • BIND 9.6-ESV support ended in January, 2014
  • BIND 9.9 Extended Support Version will be supported until June, 2017


  • DHCP 4.1-ESV was scheduled for EOL in December 2015, but we decided to continue supporting it to provide a small-footprint version
  • DHCP 4.3 is the current ESV version

Within two years of the release of an ESV we will select a new candidate. Each ESV will be supported for four (4) years, so that there is a steady flow of ESV releases.

Once the ESV designation has been assigned to a given major release we will avoid introducing any new features or functionality changes.  (Exceptions may be made where the feature is of significant benefit to the user community – but in those cases, the new functionality will be enabled via a compile-time option).  However, we will install all significant and applicable bug fixes into ESVs.

Updates will be released for supported versions approximately every six (6) months or upon announcement of major security bugs or operational fixes.

Other General Policy Guidelines

  • Standard support terms do not apply to developmental releases (such as Kea prior to release 1.0) or Alpha, Beta  and Release Candidates (RC’s).
  • Developmental releases may come out more often than supported releases.
  • Some level of support may be provided on a best effort basis through our alpha or beta tester program for selected customers and community members enrolled in those programs.
  • We reserve the right to change our version numbering for Kea.
  • We also reserve the right, based on these changes, to include some minor features in point releases (e.g. 9.8.1) for BIND and DHCP.

Last modified: September 28, 2015 at 9:16 pm