OneClick JRE Thick Client slowness due to DNS lookups - Spectrum

Products

• Network Observability
• Spectrum

Issue/Introduction

The OneClick JRE Thick client (JNLP) performs slowly, while the OneClick WebApp performs normally. This issue typically surfaces after an upgrade or network change where reverse-DNS resolution for client IP addresses is slow or failing.

Symptoms

• OneClick Java console is sluggish to load models information.
• OneClick WebApp is not impacted.
• Increasing client memory or tuning ModelRepository threads does not improve performance.
• Network traces show delays corresponding to DNS port 53 traffic or timeouts during client connection.

Environment

• Product: DX NetOps Spectrum
• Component: OneClick JRE Thick Client
• OS: All supported platforms

Cause

By default, the Spectrum Tomcat configuration may have enableLookups="true" in the server.xml file. This causes Tomcat to perform a reverse-DNS lookup to resolve the hostname of every connecting client IP. If the DNS server is slow or the client's IP subnet does not have valid PTR records, the OneClick console will hang while waiting for the DNS timeout.

Resolution

Disable DNS lookups in the Tomcat configuration to prevent resolution delays.

1. Log into the OneClick server as the user that owns the Spectrum installation.

2. Navigate to the $SPECROOT/tomcat/conf/ directory.

3. Back up the server.xml file.

4. Edit server.xml and locate the Connector elements (typically for ports 8080 and 8443).

5. Set the enableLookups parameter to false for each connector:

   enableLookups="false"

   Example: <Connector port="8080" enableLookups="false" ... />

6. Save the changes.

7. Restart the Spectrum Tomcat service.