Producer while server is offline

[TheSharpOwl]

In case I got a producer in the code and it's sending messages but the Kafka server is offline (not the consumer), does it buffer stuff ? and if yes what is the limit ? and can that limit be set ?

Also what does flush() actually do ? (what's the difference between calling it or not)

Sorry if it's already answered because I tried to google it and couldn't find my answer.