9. Write a program for DNS lookup. Given an IP address input, it should return URL and vice- versa.

Download The write up here

/import java.net.*;
import java.util.*;

public class IPDemo
{
public static void main(String[] args){
String host;
Scanner ch = new Scanner(System.in);
System.out.print("1.Enter Host Name \n2.Enter IP address \nChoice=");
int choice = ch.nextInt();
if(choice==1)
{
Scanner input = new Scanner(System.in);
System.out.print("\n Enter host name: ");
host = input.nextLine();
try {
InetAddress address = InetAddress.getByName(host);
System.out.println("IP address: " + address.getHostAddress());
System.out.println("Host name : " + address.getHostName()); 
System.out.println("Host name and IP address: " + address.toString());
}
catch (UnknownHostException ex) {
     System.out.println("Could not find " + host);
}
}
else
{
Scanner input = new Scanner(System.in);
System.out.print("\n Enter IP address: ");
host = input.nextLine();
try {
InetAddress address = InetAddress.getByName(host);
System.out.println("Host name : " + address.getHostName());
System.out.println("IP address: " + address.getHostAddress());
System.out.println("Host name and IP address: " + address.toString());

}
catch (UnknownHostException ex) {
     System.out.println("Could not find " + host);
}
}

}
}

/*OUTPUT

iotlab@iotlab-Veriton-M200-B360:~$ javac IPDemo.java 

iotlab@iotlab-Veriton-M200-B360:~$ java IPDemo 

1.Enter Host Name 

2.Enter IP address 

Choice=1

 Enter host name: www.google.com

IP address: 172.217.160.196

Host name : www.google.com

Host name and IP address: www.google.com/172.217.160.196

iotlab@iotlab-Veriton-M200-B360:~$ java IPDemo 

1.Enter Host Name 

2.Enter IP address 

Choice=2

 Enter IP address: 8.8.8.8

Host name : dns.google

IP address: 8.8.8.8

Host name and IP address: dns.google/8.8.8.8

iotlab@iotlab-Veriton-M200-B360:~$ 

*/