Friday 29 January 2016

Resolving DNS Caching Issue while Performance Testing Web Services.



How to disable DNS Caching in Load Runner to avoid misleading performance results while testing Web services.

Protocol Type:

Web Service



Scenario/Flow:

Load Runner-->WIP(Global Load Balance)-->VIP(Local Load Balancer)-->Host(Web Logic Server)

Note: WIP is a DNS service, the DNS reply can be cached locally and some load tests could give misleading results like the response time of web service request differs from the actual response time.



Issue:

Request was not reaching to WIP and it was not asking the WIP for DNS resolution or DNS lookup(translation of the unique IP address or domain of host in textual format to an IP address).



Symptom:

Local DNS Caching(Applications can cache the DNS reply, as can local DNS servers).



Resolution:

As the Web Service protocol in Load Runner does not have any option to disable DNS caching, we need to create a script using Web HTTP/HTML protocol by converting all your SOAP or JMS calls using web_custom_request in Web HTTP/HTML protocol. Once the migration is done, go to Runtime Setting > Click on Preferences under Internet Protocol group>Click Options button>Change the DNS Caching option to NO under General Tab(by default it is set to YES).

 


1 comment:

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