- doh2: add native C module for DNS-over-HTTPS (#600, !997)
- xdp: add server-side XDP support for higher UDP performance (#533, !1083)
- lower default EDNS buffer size to 1232 bytes (#538, #300, !920);
- see https://dnsflagday.net/2020/
+ see https://www.dnsflagday.net/2020/
- net: split the EDNS buffer size into upstream and downstream (!1026)
- lua-http doh: answer to /dns-query endpoint as well as /doh (!1069)
- improve resiliency against UDP fragmentation attacks (disable PMTUD) (!1061)
Get/set maximum EDNS payload size advertised in DNS packets. Different values can be configured for communication downstream (towards clients) and upstream (towards other DNS servers). Set and also get operations use values in this order.
- Default is 1232 bytes which was chosen to minimize risk of `issues caused by IP fragmentation <https://blog.apnic.net/2019/07/12/its-time-to-consider-avoiding-ip-fragmentation-in-the-dns/>`_. Further details can be found at `DNS Flag Day 2020 <https://dnsflagday.net/2020/>`_ web site.
+ Default is 1232 bytes which was chosen to minimize risk of `issues caused by IP fragmentation <https://blog.apnic.net/2019/07/12/its-time-to-consider-avoiding-ip-fragmentation-in-the-dns/>`_. Further details can be found at `DNS Flag Day 2020 <https://www.dnsflagday.net/2020/>`_ web site.
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 by DNSSEC standard :rfc:`4035`.
* Users of :ref:`control-sockets` API need to terminate each command sent to resolver with newline
character (ASCII ``\n``). Correct usage: ``cache.stats()\n``.
Newline terminated commands are accepted by all resolver versions >= 1.0.0.
-* `DNS Flag Day 2020 <https://dnsflagday.net/2020/>`_ is now effective and Knot Resolver uses
+* `DNS Flag Day 2020 <https://www.dnsflagday.net/2020/>`_ is now effective and Knot Resolver uses
maximum size of UDP answer to 1232 bytes. Please double-check your firewall,
it has to allow DNS traffic on UDP and **also TCP** port 53.
* Human readable output in interactive mode and from :ref:`control-sockets` was improved and
#define KR_DNS_DOH_PORT 443
#define KR_DNS_TLS_PORT 853
#define KR_EDNS_VERSION 0
-#define KR_EDNS_PAYLOAD 1232 /* Default UDP payload; see https://dnsflagday.net/2020/ */
+#define KR_EDNS_PAYLOAD 1232 /* Default UDP payload; see https://www.dnsflagday.net/2020/ */
#define KR_CACHE_DEFAULT_TTL_MIN (5) /* avoid bursts of queries */
#define KR_CACHE_DEFAULT_TTL_MAX (6 * 24 * 3600) /* 6 days, like the root NS TTL */