DNS caching
You can use two global configuration properties to control the caching of host name-to-numeric IP address or DNS lookup results returned from the name resolution services of the underlying operating system.
About this task
Steps
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To configure these properties, use the
dsconfig
tool.Global configuration properties and their descriptions Global configuration property Description network-address-cache-ttl
Sets the Java system property
networkaddress.cache.ttl
, and controls the length of time in seconds that a host name-to-IP address mapping can be cached. By default, it keeps resolution results for one hour (3600 seconds). This setting applies to the server and all extensions loaded by the server.network-address-outage-cache-enabled
Caches host name-to-IP address results in the event of a DNS outage. By default, this is set to true, meaning name resolution results are cached. Unexpected service interruptions might occur during planned or unplanned maintenance, network outages, or an infrastructure attack. This cache can allow the server to function during a DNS outage with minimal impact. This cache is not available to server extensions.
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To reduce delays caused by unnecessary DNS lookups, follow these recommendations:
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Maintain a connection pool in the client app rather than opening new connections for each bind.
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Add appropriate records to DNS, including PTR records.
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Add
options timeout:1
oroptions single-request
in the/etc/resolv.conf
file. -
If IPv6 requests are causing issues, add
-Djava.net.preferIPv4Stack=true
to thestart-server.java-args
line in server’sconfig/java.properties
file, so that runningbin/dsjavaproperties
and restarting the server no longer issues IPv6 PTR requests.
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