Golang : Resolve domain name to IP4 and IP6 addresses.

In this short tutorial, we will learn how to resolve (find out) the IP, IP4 and maybe IP6 addresses for a domain name. Go's standard library net package has the ResolveIPAddr function to take care of the low level stuff.

This program below will attempt to find out the given domain name's IP, IP4 and IP6 addresses.

resolveip.go

 package main

 import (
 "net"
 "flag"
 "fmt"
 "os"
 )


 func main() {
 flag.Parse()

 domain_name := flag.Arg(0) // get the first argument


 ip4address, err := net.ResolveIPAddr("ip4", domain_name)
 if err != nil {
 fmt.Println("Fail to resolve IP4", err.Error())
 os.Exit(1)
 }


 ip6address, err := net.ResolveIPAddr("ip6", domain_name)
 if err != nil {
 fmt.Println("Fail to resolve IP6", err.Error())
 os.Exit(1)
 }

 fmt.Printf("Resolved %s to IP4[%s] and IP6[%s] \n", domain_name, ip4address.String(), ip6address.String())
 os.Exit(0) // exit gracefully

 }

Executing go run resolveip.go www.google.com will give the following output

Resolved www.google.com to IP4[74.125.130.105] and IP6[2404:6800:4003:c01::6a]

However, let's us try with different domain name and see what's the different

Executing go run resolveip.go www.amazon.com will give the following output

Fail to resolve IP6 no suitable address found

exit status 1

Hope this tutorial will be helpful to you in learning Go.