I ran into a problem after deploying kafka on my Kubernetes cluster. Whenever my client was using a "group-id", it would fail and get back errors about Marking some broker dead. The reason this happened was that the default offsets.topic.replication.factor is 1 whereas min.insync.replicas is set to 2.
Some more details can be found here.
The fix was to either change the min.insync.replicas to 1 or set the offsets.topic.replication.factor to 2.