.. SPDX-License-Identifier: GPL-3.0-or-later

.. _config-nsid:

Name Server Identifier (NSID)
=============================

Knot Resolver provides server-side support for :rfc:`5001`
which allows DNS clients to request resolver to send back its NSID
along with the reply to a DNS request.
This is useful for debugging larger resolver farms
(e.g. when using :ref:`systemd-multiple-instances`, anycast or load balancers).

NSID value can be configured in the resolver's configuration file:

.. code-block:: yaml

   nsid: kres1

.. note::

   When running with multiple workers, each worker adds its own identifier to the end of the NSID.