---
title: Domain Name Service (DNS) caching
description: If needed, two global configuration properties can be used to control the caching of host name-to-numeric IP address (DNS lookup) results returned from the name resolution services of the underlying operating system. Use the dsconfig tool to configure these properties.
component: pingdirectory
version: 11.0
page_id: pingdirectory:pingdatasync_server_administration_guide:pd_sync_dns_caching
canonical_url: https://docs.pingidentity.com/pingdirectory/11.0/pingdatasync_server_administration_guide/pd_sync_dns_caching.html
revdate: September 13, 2023
---

# Domain Name Service (DNS) caching

If needed, two global configuration properties can be used to control the caching of host name-to-numeric IP address (DNS lookup) results returned from the name resolution services of the underlying operating system. Use the `dsconfig` tool to configure these properties.

* 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. The default behavior is to keep 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. This is set to `true` by default, 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.

To reduce delays because of unnecessary DNS lookups, follow these recommendations:

* Maintain a connection pool in the client app rather than opening new connections for each bind.

* Add appropriate records to DNS, including PTR records.

* Add `options timeout:1` or `options single-request` in `/etc/resolv.conf`.

* If IPv6 requests specifically are causing issues, add `-Djava.net.preferIPv4Stack=true` to the `start-server.java-args` line in PingDirectory's `config/java.properties` so that running `bin/dsjavaproperties` and restarting the server will no longer issue IPv6 PTR requests.