what quickest proceed detect an unreachable horde java?

i fastest many accurate duty boolean isreachable(string host, int port) passes following junit tests underneath conditions below. timeout values specified junit exam itself, competence deliberate "unreachable."

please note: answers contingency platform-independent. means inetaddress.isreachable(int timeout) going work, given relies pier 7 ping windows (icmp ping being an undocumented duty windows), pier blocked setup.

lan setup:

• thismachine (192.168.0.100)


• othermachine (192.168.0.200)


• no accessory called nomachine ip 192.168.0.222 (always unreachable)


• both machines controlling apache tomcat pier 8080; ports unreachable (including pier 7)


• example.com (208.77.188.166) controlling webserver pier 80 wholly reachable lan connected internet

occasionally, lan away internet box wholly internal machines called ip castle reachable (all others unreachable; there's dns).

all tests run thismachine.

@test(timeout=1600) // ~320ms per (should illusory better)
public vacant testlocalhost() {
    // always strech ourselves.
    asserttrue(isreachable("localhost", 8080));
    asserttrue(isreachable("127.0.0.1", 8080));
    asserttrue(isreachable("thismachine", 8080)); // even there's dns!
    asserttrue(isreachable("192.168.0.100", 8080));

    assertfalse(isreachable("localhost", 80)); // zero port.
}

@test(timeout=5500) // ~1867ms per (should means better)
public vacant testlan() {
    asserttrue(isreachable("192.168.0.200", 8080)); // always connected lan.
    assertfalse(isreachable("192.168.0.222", 8080)); // such machine.
    assertfalse(isreachable("nomachine", 8080)); // such machine.
}

the following exam wholly run lan disconnected internet.

@test(timeout=5600) // ~1867ms per (reasonable?)
public vacant testnodns() {
    assertfalse(isreachable("othermachine", 8080)); // dns.
    assertfalse(isreachable("example.com", 80)); // dns & internet.
    assertfalse(isreachable("208.77.188.166", 80)); // internet.
}

the following exam wholly run lan connected internet.

@test(timeout=5600) // ~1867ms per (reasonable?)
public vacant testhavedns() {
    asserttrue(isreachable("othermachine", 8080)); // dns resolves internal names.
    asserttrue(isreachable("example.com", 80)); // dns available.
    asserttrue(isreachable("208.77.188.166", 80)); // internet available.
}