title: Apache Kafka - DNS resolution failed for url in bootstrap.servers (Failed to construct kafka producer)
body: <p>I have a problem to construct kafka producer with hostname.
  Here's what I did.</p>
  
  <p>1) I set the host.name, port config to <em>server.properties</em></p>
  
  <pre><code>listeners=PLAINTEXT://192.168.0.102:9092
  
  port=9092
  host.name=server002.sep.com
  </code></pre>
  
  <p>2) I add the host ip and alias name to <em>/etc/hosts</em></p>
  
  <pre><code>127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
  ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
  
  192.168.0.102 server002.sep.com
  </code></pre>
  
  <p>3) set up a firewall using iptables</p>
  
  <pre><code>-A INPUT -p tcp -m tcp --dport 3888 -j ACCEPT
  -A INPUT -p tcp -m tcp --dport 2888 -j ACCEPT
  -A INPUT -p tcp -m tcp --dport 2181 -j ACCEPT
  -A INPUT -p tcp -m tcp --dport 9092 -j ACCEPT
  </code></pre>
  
  <p>4) I construct the producer with below configuration.
  I set the "hostname:port" instead of "ip:port".</p>
  
  <pre><code>  props = new Properties();
  
  **props.put("bootstrap.servers", "server002.sep.com:9092");
    props.put("acks", "0");
    props.put("retries", "0");
  </code></pre>
  
  <p>Exception occurred while running the producer.
  Here's the error log.
  I don't understand why fail to construct kafka producer.
  please check it. :)</p>
  
  <pre><code>Exception in thread "main" org.apache.kafka.common.KafkaException: **Failed to construct kafka producer**
  at org.apache.kafka.clients.producer.KafkaProducer.&lt;init&gt;(KafkaProducer.java:321)
  at org.apache.kafka.clients.producer.KafkaProducer.&lt;init&gt;(KafkaProducer.java:181)
  at com.lgcns.sep.kafka.producer.MessageSender.createProducer(MessageSender.java:47)
  at com.lgcns.sep.kafka.producer.MessageSender.getInstance(MessageSender.java:22)
  at com.lgcns.jartest.producerTest.main(producerTest.java:27)
  
  Caused by: org.apache.kafka.common.config.ConfigException: **DNS resolution failed for url in bootstrap.servers**: server002.sep.com:9092
  at org.apache.kafka.clients.ClientUtils.parseAndValidateAddresses(ClientUtils.java:49)
  at org.apache.kafka.clients.producer.KafkaProducer.&lt;init&gt;(KafkaProducer.java:269)
  ... 4 more
  </code></pre>