报错：Connection to node -1 could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)

报错背景：

启动kafka消费者之后出现这种报错，持续打印相同信息。

报错现象：

[root@master kafka_2.11-1.1.1]# /opt/kafka/kafka_2.11-1.1.1/bin/kafka-console-consumer.sh --bootstrap-server master:9092 --topic alarmHis
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/bigdata/app/.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/bigdata/app/bigdata-1.0-SNAPSHOT-jar-with-dependencies.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/opt/kafka/kafka_2.11-1.1.1/libs/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
[2019-05-23 08:35:56,555] WARN [Consumer clientId=consumer-1, groupId=console-consumer-68734] Connection to node -1 could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2019-05-23 08:35:56,608] WARN [Consumer clientId=consumer-1, groupId=console-consumer-68734] Connection to node -1 could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2019-05-23 08:35:56,709] WARN [Consumer clientId=consumer-1, groupId=console-consumer-68734] Connection to node -1 could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2019-05-23 08:35:56,911] WARN [Consumer clientId=consumer-1, groupId=console-consumer-68734] Connection to node -1 could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
[2019-05-23 08:35:57,364] WARN [Consumer clientId=consumer-1, groupId=console-consumer-68734] Connection to node -1 could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)

报错原因：

不明。

报错解决：