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COREDNS-MULTISOCKET(7)		CoreDNS	Plugins		COREDNS-MULTISOCKET(7)

NAME
       multisocket  - allows to	start multiple servers that will listen	on one
       port.

DESCRIPTION
       With multisocket, you can define	the number of servers that will	listen
       on the same port. The SO_REUSEPORT socket option	allows to open	multi-
       ple  listening sockets at the same address and port. In this case, ker-
       nel distributes incoming	connections between sockets.

       Enabling	this option allows to start multiple servers, which  increases
       the  throughput	of  CoreDNS in environments with a large number	of CPU
       cores.

SYNTAX
	      multisocket [NUM_SOCKETS]

       •   NUM_SOCKETS - the number of servers that will listen	on  one	 port.
	   Default value is equal to GOMAXPROCS.

EXAMPLES
       Start 5 TCP/UDP servers on the same port.

	      .	{
		  multisocket 5
		  forward . /etc/resolv.conf
	      }

       Do  not	define NUM_SOCKETS, in this case it will take a	value equal to
       GOMAXPROCS.

	      .	{
		  multisocket
		  forward . /etc/resolv.conf
	      }

RECOMMENDATIONS
       The tests of the	multisocket plugin, which were conducted for NUM_SOCK-
       ETS from	1 to 10, did not reveal	any side effects or performance	degra-
       dation.

       This means that the multisocket plugin can be used with a default value
       that is equal to	GOMAXPROCS.

       However,	to achieve the best results, it	is recommended to consider the
       specific	environment and	plugins	used in	CoreDNS. To determine the  op-
       timal  configuration, it	is advisable to	conduct	performance tests with
       different NUM_SOCKETS, measuring	Queries	Per Second  (QPS)  and	system
       load.

       If conducting such tests	is difficult, follow these recommendations: 1.
       Determine  the maximum CPU consumption of CoreDNS server	without	multi-
       socket plugin. Estimate how much	CPU CoreDNS
	  actually consumes in specific	environment under  maximum  load.   2.
       Align  NUM_SOCKETS  with	the estimated CPU usage	and CPU	limits or sys-
       tem's available resources.
	  Examples:
	  - If CoreDNS consumes	4 CPUs and 8 CPUs are available, set NUM_SOCK-
       ETS to 2.
	  - If CoreDNS	consumes  8  CPUs  and	64  CPUs  are  available,  set
       NUM_SOCKETS to 8.

LIMITATIONS
       The SO_REUSEPORT	socket option is not available for some	operating sys-
       tems. It	is available since Linux Kernel	3.9 and	not available for Win-
       dows at all.

       Using this plugin with a	system that does not support SO_REUSEPORT will
       cause an	address	already	in use error.

CoreDNS				   May 2025		COREDNS-MULTISOCKET(7)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=coredns-multisocket&sektion=7&manpath=FreeBSD+Ports+15.0>

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