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COREDNS-K8S_EXTERNAL(7) 	 CoreDNS Plugins	 COREDNS-K8S_EXTERNAL(7)

NAME
     k8s_external - resolves load balancer, external IPs from outside Kubernetes
     clusters and if enabled headless services.

DESCRIPTION
     This  plugin  allows  an  additional  zone  to  resolve the external IP ad-
     dress(es) of a Kubernetes service and headless  services.	This  plugin  is
     only useful if the kubernetes plugin is also loaded.

     The  plugin  uses	an  external zone to resolve in-cluster IP addresses. It
     only handles queries for A, AAAA, SRV, and PTR records; To make it a proper
     DNS zone, it handles SOA and NS queries for the apex of the zone.

     By default the apex of the zone will look like the following (assuming  the
     zone used is example.org):

	    example.org.    5 IN    SOA ns1.dns.example.org. hostmaster.example.org. (
			    12345      ; serial
			    14400      ; refresh (4 hours)
			    3600       ; retry (1 hour)
			    604800     ; expire (1 week)
			    5	       ; minimum (4 hours)
			    )
	    example.org        5 IN    NS ns1.dns.example.org.

	    ns1.dns.example.org.  5 IN	A    ....
	    ns1.dns.example.org.  5 IN	AAAA ....

     Note  that we use the dns subdomain for the records DNS needs (see the apex
     directive). Also note the SOA's serial number is static. The  IP  addresses
     of the nameserver records are those of the CoreDNS service.

     The  k8s_external plugin handles the subdomain dns and the apex of the zone
     itself; all other queries are resolved to addresses in the cluster.

SYNTAX
	    k8s_external [ZONE...]

     *	 ZONES zones k8s_external should be authoritative for.

     If you want to change the apex domain or use a different TTL  for	the  re-
     turned records you can use this extended syntax.

	    k8s_external [ZONE...] {
		apex APEX
		ttl TTL
	    }

     *	 APEX  is  the name (DNS label) to use for the apex records; it defaults
	 to dns.

     *	 ttl allows you to set a custom TTL for  responses.  The  default  is  5
	 (seconds).

     If  you want to enable headless service resolution, you can do so by adding
     headless option.

	    k8s_external [ZONE...] {
		headless
	    }

     *	 if there is a headless service with external IPs set, external IPs will
	 be resolved

     If the queried domain does not exist, you can fall through to  next  plugin
     by adding the fallthrough option.

	    k8s_external [ZONE...] {
		fallthrough [ZONE...]
	    }

EXAMPLES
     Enable names under example.org to be resolved to in-cluster DNS addresses.

	    . {
	       kubernetes cluster.local
	       k8s_external example.org
	    }

     With  the	Corefile  above,  the following Service will get an A record for
     test.default.example.org with the IP address 192.168.200.123.

	    apiVersion: v1
	    kind: Service
	    metadata:
	     name: test
	     namespace: default
	    spec:
	     clusterIP: None
	     externalIPs:
	     - 192.168.200.123
	     type: ClusterIP

     The k8s_external plugin can be used in conjunction with the transfer plugin
     to enable zone transfers.	Notifies are not supported.

		 . {
		     transfer example.org {
			 to *
		     }
		     kubernetes cluster.local
		     k8s_external example.org
		 }

     With the fallthrough option, if the queried domain does not exist, it  will
     be passed to the next plugin that matches the zone.

	    . {
	       kubernetes cluster.local
	       k8s_external example.org {
		 fallthrough
	       }
	       forward . 8.8.8.8
	    }

     For some background see resolve external IP address <https://github.com/ku-
     bernetes/dns/issues/242>.	And A records for services with Load Balancer IP
     <https://github.com/coredns/coredns/issues/1851>.

CoreDNS 			   March 2026		 COREDNS-K8S_EXTERNAL(7)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=coredns-k8s_external&sektion=7&manpath=FreeBSD+Ports+15.1.quarterly>

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