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

DNS protocol tweaks
-------------------

Following settings change low-level details of DNS protocol implementation.
Default values should not be changed except for very special cases.

.. function:: net.bufsize([udp_bufsize])

   Get/set maximum EDNS payload size advertised in DNS packets. Default is 4096 bytes and the default will be lowered to value around 1220 bytes in future, once `DNS Flag Day 2020 <https://dnsflagday.net/>`_ becomes effective.

   Minimal value allowed by standard :rfc:`6891` is 512 bytes, which is equal to DNS packet size without Extension Mechanisms for DNS. Value 1220 bytes is minimum size required in DNSSEC standard :rfc:`4035`.

   Example output:

   .. code-block:: lua

	> net.bufsize(4096)
	nil
	> net.bufsize()
	4096

.. include:: ../modules/workarounds/README.rst