public static String extractZoneFromHostName(String hostName) {
        Matcher matcher = ZONE_RE.matcher(hostName);
        if (matcher.matches()) {
            return matcher.group(2);
        }
        return null;
    }
@Test
    public void testExtractZoneFromHostName() throws Exception {
        assertThat(ResolverUtils.extractZoneFromHostName("us-east-1c.myservice.net"), is(equalTo("us-east-1c")));
        assertThat(ResolverUtils.extractZoneFromHostName("txt.us-east-1c.myservice.net"), is(equalTo("us-east-1c")));
    }