.. SPDX-License-Identifier: GPL-3.0-or-later
.. _mod-nsid:
Name Server Identifier (NSID)
=============================
Module ``nsid`` 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:: lua
modules.load('nsid')
nsid.name('instance 1')
.. tip:: When dealing with Knot Resolver running in `multiple instances`
managed with systemd see :ref:`instance-specific-configuration`.
You can also obtain configured NSID value:
.. code-block:: lua
> nsid.name()
'instance 1'
The module can be disabled at run-time:
.. code-block:: lua
modules.unload('nsid')
