Github user mfenes commented on the issue:
https://github.com/apache/zookeeper/pull/451
Looking at the static initialization block in InetAddressCachePolicy more
deeply, the default TTL is 30 seconds if there is no SecurityManager installed.
So caching a positive lookup forever in the Java-level cache is the default
only if there is a SecurityManager installed and the TTL is not overridden by
"networkaddress.cache.ttl" to a different value.
Default caching policy for a negative lookup is 0 (never cache).
Now the only question is whether 30 seconds default caching is ok or too
much for ZK.
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