public static boolean isMulticastAddress(String host) {
        int i = host.indexOf('.');
        if (i > 0) {
            String prefix = host.substring(0, i);
            if (StringUtils.isNumber(prefix)) {
                int p = Integer.parseInt(prefix);
                return p >= 224 && p <= 239;
            }
        }
        return false;
    }
@Test
    void testIsMulticastAddress() {
        assertTrue(NetUtils.isMulticastAddress("224.0.0.1"));
        assertFalse(NetUtils.isMulticastAddress("127.0.0.1"));
    }