Find DNS records programmatically

A and AAAA

The net.LookupIP() function accepts a string(domain-name) and returns a slice of net.IP objects that contains host's IPv4 and IPv6 addresses.

package main
 
import (
	"fmt"
	"net"
)
 
func main() {
	iprecords, _ := net.LookupIP("facebook.com")
	for _, ip := range iprecords {
		fmt.Println(ip)
	}
}

2a03:2880:f12f:83:face:b00c:0:25de
31.13.79.35

Canonical Name (CNAME)

This is the abbreviation for canonical name. CNAMEs are essentially domain and subdomain text aliases to bind traffic. The net.LookupCNAME() function accepts a host-name(m.facebook.com) as a string and returns a single canonical domain name for the given host.

package main
 
import (
	"fmt"
	"net"
)
 
func main() {
	cname, _ := net.LookupCNAME("m.facebook.com")
	fmt.Println(cname)
}

star-mini.c10r.facebook.com.

PTR (pointer)

These records provide the reverse binding from addresses to names. PTR records should exactly match the forward maps. The net.LookupAddr() function performs a reverse finding for the address and returns a list of names that map to the given address.

package main
 
import (
	"fmt"
	"net"
)
 
func main() {
	ptr, _ := net.LookupAddr("6.8.8.8")
	for _, ptrvalue := range ptr {
		fmt.Println(ptrvalue)
	}
}

tms_server.yuma.army.mil

Name Server (NS)

The NS records describe the authorized name servers for the zone. The NS also delegates subdomains to other organizations on zone files. The net.LookupNS() function takes a domain name(facebook.com) as a string and returns DNS-NS records as a slice of NS structs.

package main
 
import (
	"fmt"
	"net"
)
 
func main() {
	nameserver, _ := net.LookupNS("facebook.com")
	for _, ns := range nameserver {
		fmt.Println(ns)
	}
}

&{a.ns.facebook.com.} &{b.ns.facebook.com.}

MX records

These records identify the servers that can exchange emails. The net.LookupMX() function takes a domain name as a string and returns a slice of MX structs sorted by preference. An MX struct is made up of a Host as a string and Pref as a uint16.

package main
 
import (
	"fmt"
	"net"
)
 
func main() {
	mxrecords, _ := net.LookupMX("facebook.com")
	for _, mx := range mxrecords {
		fmt.Println(mx.Host, mx.Pref)
	}
}

msgin.vvv.facebook.com. 10

SRV service record

The LookupSRV function tries to resolve an SRV query of the given service, protocol, and domain name. The second parameter is "tcp" or "udp". The returned records are sorted by priority and randomized by weight within a priority.

package main
 
import (
	"fmt"
	"net"
)
 
func main() {
	cname, srvs, err := net.LookupSRV("xmpp-server", "tcp", "golang.org")
	if err != nil {
		panic(err)
	}
 
	fmt.Printf("\ncname: %s \n\n", cname)
 
	for _, srv := range srvs {
		fmt.Printf("%v:%v:%d:%d\n", srv.Target, srv.Port, srv.Priority, srv.Weight)
	}
}

cname: _xmpp-server._tcp.golang.org.

TXT records

This text record stores information about the SPF that can identify the authorized server to send email on behalf of your organization. The net.LookupTXT() function takes a domain name(facebook.com) as a string and returns a list of DNS TXT records as a slice of strings.

package main
 
import (
	"fmt"
	"net"
)
 
func main() {
	txtrecords, _ := net.LookupTXT("facebook.com")
 
	for _, txt := range txtrecords {
		fmt.Println(txt)
	}
}

v=spf1 redirect=_spf.facebook.com