Troubleshooting
Problem
Networks that use DNS load balanced hostnames experience failures when the DNS entry is updated while the WebSphere web server plug-in is running. The WebSphere web server plug-in does not dynamically detect the DNS update. If the modified DNS hostname is defined as an application server in the web server plug-in configuration, the plug-in module does not learn the new address until the module is restarted.
Cause
For improved performance, the web server plug-in resolves the back-end server hostname when the web server is started or the plug-in is reloaded due to a detected change in the configuration file.
Resolving The Problem
One of the following methods can be used to force the WebSphere web server plug-in to detect the DNS changes:
- Edit and save the plugin-cfg.xml file with no changes. The location of the plugin-cfg.xml can be found in the web server configuration file. The plug-in module will issue a reload and resolve the hostnames to their current IP addresses after the current plug-in RefreshInterval property expires.
- Use the touch command to update the timestamp of plugin-cfg.xml. The plug-in module will issue a reload and resolve the hostnames to their current IP addresses after the current plug-in RefreshInterval property expires.
- Issue a graceful restart of your web server.
If an automatic solution is required, create a cron job to run periodically that issues a touch on the configuration file. Another option available is to create a script that monitors the DNS record (nslookup). When a change is detected, the script then issues the appropriate action to reload the web server plug-in.
Document Location
Worldwide
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Document Information
Modified date:
23 December 2021
UID
ibm16436093