Java DNS lookup test

Main.java

package org.example;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Hashtable;
import java.util.List;
import javax.naming.NamingEnumeration;
import javax.naming.directory.Attribute;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;

public class Main {

  public static void main(String[] args) {
    System.out.println("Started.");
    long start = System.nanoTime();
    try {
      final String recordType = args[0];
      final String name = args[1];

      Class.forName("javax.naming.directory.InitialDirContext");
      Class.forName("com.sun.jndi.dns.DnsContextFactory");

      System.out.println("Querying " + recordType + " records for " + name);

      String[] rrType = new String[]{recordType};
      List<String> records = new ArrayList<>();

      Hashtable<String, String> env = new Hashtable<>();
      env.put("com.sun.jndi.ldap.connect.timeout", "5000");
      env.put("com.sun.jndi.ldap.read.timeout", "5000");
      DirContext dirContext = new InitialDirContext(env);

      javax.naming.directory.Attributes attrs = dirContext.getAttributes("dns:///" + name, rrType);
      NamingEnumeration<? extends Attribute> rrGroups = attrs.getAll();

      while (rrGroups.hasMore()) {
        Attribute rrEntry = rrGroups.next();
        assert Arrays.asList(rrType).contains(rrEntry.getID());
        NamingEnumeration<?> rrValues = rrEntry.getAll();
        while (rrValues.hasMore()) {
          records.add(String.valueOf(rrValues.next()));
        }
        rrValues.close();
      }
      rrGroups.close();
      dirContext.close();

      System.out.println("Found " + records.size() + " record(s)");
      for (String rec : records) {
        System.out.println(rec);
      }
    } catch (Exception e) {
      System.out.println("Error: " + e.getLocalizedMessage());
      e.printStackTrace(System.out);
    } finally {
      System.out.println("Finished in " + ((System.nanoTime() - start) / 1000000) + " ms.");
    }
  }
}