IsReachable(int timeout) allways needs more than 1000ms to complete

Question

I know that issues with pinging in Java have been discussed many times but after searching through numerous threads I haven't come up with a solution yet. In addition, my problem is specific.
I'm new to Java and I've heard that you can't do a real ping unless you use native code. Then I discovered the isReachable method which was supposed to solve most of the pinging issues.
My problem is that every time, on any host, this method needs >=1000ms to complete. In the following code, 'pinging' the localhost returns 1000ms in most cases, sometimes a bit more. But never under 1s.
public class NewMain {
    static InetAddress ip;
    public static void main(String[] args) throws Exception {
        ip= InetAddress.getByName("localhost");
        long start= System.currentTimeMillis();
        boolean reachable= ip.isReachable(2000);
        long end= System.currentTimeMillis();
        if (reachable)
            System.out.println(end-start+"ms");      
}From what I could find on this matter, some people got correct results with similar methods (~0ms) while some others got results similar to mine (~1000ms). I didn't try to implement my own ping() method yet because isReachable sounds just right for my needs, only if it worked right.
I would appreciate if you could run this code and post the results along with your JDK version.
I am using JDK 1.6.0 .

Answer 1

Pardon my ignorance, but it is obvious that I don't
know much on the matter. Ping just always seemed like
a simplest and fastest way to determine internet
connection functionality. If I need to write a whole
Network Management System just to test Internet
connectivity... Well, it just doesn't sound right.Yes it is simple. Deceptively so.
Ping can return success even though the server is totally inoperable.
>
I would appreciate if you could give me a hint on how
to make a simple connection testing program without
using ping.If at all possible I wouldn't want to do it simply. No one cares if the equipement is up - what they care about is whether it is working or not.
For network infrastructue equipment such as routers, etc (including power supplies) SNMP almost always exists. Particularily these days I doubt you can buy newer equipment where that wouldn't be the case. Or they often have mini servers (such as http) as well.
If you are just testing standard servers then there are two ways
- Connective aware servers like htttp servers. For these you should make an actual request. The more complicated the better. For example do an http request that returns dynamic data rather than one that returns static data.
- Non-connective aware servers, then add a management API. This can be justified not just from the verification point but also from the remote admin management point of view. Implement a "are you ok" message. The server should either test something with this message or should be gathering information during process which it can return.