class DnsNameResolver extends InetNameResolver {

    @Override
    public void close() {
        if (ch.isOpen()) {
            ch.close();
        }
    }

    public  DnsNameResolver(
            EventLoop eventLoop,
            ChannelFactory<? extends DatagramChannel> channelFactory,
            final DnsCache resolveCache,
            DnsCache authoritativeDnsServerCache,
            DnsQueryLifecycleObserverFactory dnsQueryLifecycleObserverFactory,
            long queryTimeoutMillis,
            ResolvedAddressTypes resolvedAddressTypes,
            boolean recursionDesired,
            int maxQueriesPerResolve,
            boolean traceEnabled,
            int maxPayloadSize,
            boolean optResourceEnabled,
            HostsFileEntriesResolver hostsFileEntriesResolver,
            DnsServerAddressStreamProvider dnsServerAddressStreamProvider,
            String[] searchDomains,
            int ndots,
            boolean decodeIdn);

}