ClickHouse/tests/integration/test_distributed_ddl_parallel/configs/remote_servers.xml

<clickhouse>
<remote_servers>
    <cluster_a>
        <shard>
            <replica>
                <host>n1</host>
                <port>9000</port>
            </replica>
        </shard>
        <shard>
            <replica>
                <host>n2</host>
                <port>9000</port>
            </replica>
        </shard>
    </cluster_a>
    <cluster_b>
        <shard>
            <replica>
                <host>n3</host>
                <port>9000</port>
            </replica>
        </shard>
        <shard>
            <replica>
                <host>n4</host>
                <port>9000</port>
            </replica>
        </shard>
    </cluster_b>
</remote_servers>
</clickhouse>