/*
 * Copyright 2017 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.resolver.dns;

import io.netty.util.internal.UnstableApi;

Provides an opportunity to override which DnsServerAddressStream is used to resolve a specific hostname. 

For example this can be used to represent /etc/resolv.conf and

/etc/resolver.
/**
 * Provides an opportunity to override which {@link DnsServerAddressStream} is used to resolve a specific hostname.
 * <p>
 * For example this can be used to represent <a href="https://linux.die.net/man/5/resolver">/etc/resolv.conf</a> and
 * <a href="https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man5/resolver.5.html">
 * /etc/resolver</a>.
 */
@UnstableApi
public interface DnsServerAddressStreamProvider {
    
Ask this provider for the name servers to query for hostname. 
Params:
hostname – The hostname for which to lookup the DNS server addressed to use. If this is the final DnsServerAddressStreamProvider to be queried then generally empty string or '.' correspond to the default DnsServerAddressStream.
Returns:
The DnsServerAddressStream which should be used to resolve hostname./**
     * Ask this provider for the name servers to query for {@code hostname}.
     * @param hostname The hostname for which to lookup the DNS server addressed to use.
     *                 If this is the final {@link DnsServerAddressStreamProvider} to be queried then generally empty
     *                 string or {@code '.'} correspond to the default {@link DnsServerAddressStream}.
     * @return The {@link DnsServerAddressStream} which should be used to resolve {@code hostname}.
     */
    DnsServerAddressStream nameServerAddressStream(String hostname);
}