private String resolveIpAddress(String hostname, DirContext ctx) {
		try {
			Attribute dnsRecord = lookup(hostname, ctx, "A");
			// There should be only one A record, therefore it is save to return
			// only the first.
			return dnsRecord.get().toString();
		}
		catch (NamingException e) {
			throw new DnsLookupException("DNS lookup failed for: " + hostname, e);
		}

	}