In Kafka it will fallback to a different advertised listener if one of them is not available. This is required for us to enable a stretched cluster (brokers on the cluster 1 try to resolve to internal address before trying external address for brokers on cluster 2, vice versa).
Would there be a significant performance penalty when setting up like this, especially if its by design?
I guess it does a nslookup, and if it fails it tries the next advertised listener in the list.