@Override
    public Optional<String> resolveHostname(String ipAddress) {
        try {
            // TODO(mpolden): Use lookupName instead. IP address must be translated to its reverse
            //                notation first.
            String hostname = InetAddress.getByName(ipAddress).getHostName();
            return InetAddresses.isInetAddress(hostname) ? Optional.empty() : Optional.of(hostname);
        } catch (UnknownHostException ignored) {
        }
        return Optional.empty();
    }
Implementation of a name resolver that always uses a DNS server to resolve the given name. The intention is to avoid
possibly incorrect/incomplete records in /etc/hosts.

@author mpolden
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/persistence/DnsNameResolver.java