dongjoon-hyun commented on PR #58283:
URL: https://github.com/apache/spark/pull/58283#issuecomment-5416834245

   One more note on the motivation section, which no longer matches `master`.
   
   Since Spark 4.3 (SPARK-57351), `spark.kubernetes.executor.useDriverPodIP` is 
enabled by default, so executor pods connect to the driver RPC endpoint via the 
driver pod IP rather than the driver's K8s Service DNS name:
   
   
https://github.com/apache/spark/blob/841f3a0332d/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/features/BasicExecutorFeatureStep.scala#L56-L61
   
   So "each executor startup generates these spurious failed lookups" is not 
accurate for the default configuration on `master` anymore. What still resolves 
`spark.driver.host` is mainly the driver's advertised BlockManager address that 
executors use for block transfers:
   
   
https://github.com/apache/spark/blob/841f3a0332d/core/src/main/scala/org/apache/spark/SparkEnv.scala#L718-L720
   
   and those lookups are additionally subject to the JVM DNS cache.
   
   Could you update the description to describe the paths that still resolve 
the name on `master`, and share the measured effect on a current build (e.g. 
CoreDNS NXDOMAIN counts before/after)? Also, the test section mentions patching 
a jar manually. Which Spark version was that built from? If it predates 4.3, 
the observed NXDOMAIN volume would be from the driver service path that is no 
longer the default.
   


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