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Oct 2, 2025
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Added DNS cache settings to JVM settings doc #135696

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Added DNS cache settings to JVM settings doc
eedugon Sep 30, 2025
017c98a
Update docs/reference/elasticsearch/jvm-settings.md
eedugon Oct 2, 2025
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Merge branch 'main' into eedugon-patch-1
eedugon Oct 2, 2025
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13 changes: 13 additions & 0 deletions docs/reference/elasticsearch/jvm-settings.md
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Expand Up @@ -200,3 +200,16 @@ docker run -e ES_JAVA_OPTS="$MY_OPTS" # etc
By default, {{es}} configures the JVM to write fatal error logs to the default logging directory. On [RPM](docs-content://deploy-manage/deploy/self-managed/install-elasticsearch-with-rpm.md) and [Debian](docs-content://deploy-manage/deploy/self-managed/install-elasticsearch-with-debian-package.md) packages, this directory is `/var/log/elasticsearch`. On [Linux and MacOS](docs-content://deploy-manage/deploy/self-managed/install-elasticsearch-from-archive-on-linux-macos.md) and [Windows](docs-content://deploy-manage/deploy/self-managed/install-elasticsearch-with-zip-on-windows.md) distributions, the `logs` directory is located under the root of the {{es}} installation.

These are logs produced by the JVM when it encounters a fatal error, such as a segmentation fault. If this path is not suitable for receiving logs, modify the `-XX:ErrorFile=...` entry in [`jvm.options`](#set-jvm-options).

## DNS cache settings [networkaddress-cache-ttl]

{{es}} runs with a security manager in place. With a security manager in place, the JVM defaults to caching positive hostname resolutions indefinitely and defaults to caching negative hostname resolutions for ten seconds.

{{es}} overrides this behavior with default values to cache positive lookups for sixty seconds, and to cache negative lookups for ten seconds. These values should be suitable for most environments, including environments where DNS resolutions vary with time.

If these default values are not suitable, you can edit them:
* Cache positive lookups: `es.networkaddress.cache.ttl`
* Cache negative lookups: `es.networkaddress.cache.negative.ttl`

The values [`networkaddress.cache.ttl=<timeout>`](https://docs.oracle.com/javase/8/docs/technotes/guides/net/properties.md) and [`networkaddress.cache.negative.ttl=<timeout>`](https://docs.oracle.com/javase/8/docs/technotes/guides/net/properties.md) in the [Java security policy](https://docs.oracle.com/javase/8/docs/technotes/guides/security/PolicyFiles.md) are ignored by {{es}} unless you remove the settings for `es.networkaddress.cache.ttl` and `es.networkaddress.cache.negative.ttl`.

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