/*
 * DNSResolver.java
 *
 * Created on November 16, 2002, 5:17 AM
 */

/**
 *
 * @author  nathan Balon
 * IS 375
 * Assignment 7
 * DNS and IP look up
 * @version 
 */
import java.net.InetAddress;

public class DNSResolver {
    
    public static void main(String [] args){
        if(args.length != 1){
            System.err.println("Usage: DNSResolver [ <name> | <address>]");
            System.exit(1);
        }
        
        boolean isReverseLookup = Character.isDigit(args[0].charAt(0));
        
        try{
            InetAddress [] addresses = InetAddress.getAllByName(args[0]);
            for (int i = 0; i < addresses.length; i++){
                 if (isReverseLookup){
                     System.out.println(addresses[i].getHostAddress() +
                                      " resolves to " +
                                      addresses[i].getHostName());
                 }
                 else{
                     System.out.println(addresses[i].getHostName() +
                                       " resolves to " +
                                       addresses[i].getHostAddress());
                } 
            }           
        }
        
        catch (java.net.UnknownHostException e){
            System.err.println("Cannot Resolve " + args[0]);
            System.exit(1);
        }
        
        catch(java.lang.SecurityException e){
            System.err.println("A security manager has been installed and the " +
                               "resolve java.net.SocketPermission has not " +
                               "been granted");
            System.exit(1);
        }
    }      
}