Friday, April 26, 2013

Websphere Interview questions and answers

 Interview questions vary from company to company and also depends on the person.Some expect crisp answers while others expect detailed one.So its always better to understand any concepts in depth.

IBM  Websphere administrator Interview Questions:

1.Tell about your day to day work activities.
  Please explain the work you do regularly and you are more familiar with.Explain in detail
all the stuffs 
ex.Deployment and configuration of application,resource creations and performance management.

2.what is the maximum heap size can be set  for 32 bit and 64 bit JVM?
   2^32 that is equal to 4GB for 32 bit 
   2^64 that is equal to 32GB for 64 bit theoretically.
For better understanding for JVM heap allocation please check the link below

3.What is Garbage collection and the policy supported ?
It is process of freeing unused objects automatically by java and release the memory back for the application.
Refer ibm system mags link for tuning garbage collection
Tuning garbage collection for performance

4.Garbage collection Policy:
In each websphere application server it has default garbage collection policy.In older versions like 6 there is garbage collection policy likee optthruput was there .In optthruput there are no separate space for young and old objects so the pause time will be longer.To prevent this in higher versions a new policy was introduced called gencon (generational and conncurrent).
Refer the below link for details
Gencon garbage collection policy
IBM JVM tuning – gencon GC policy

5.How static content and dynamic content was serviced?
   Static content will be serviced by webserver to improve performance.If fileservingenabled property is set to 'false' in the  ibm-web-ext.xmi file of the web application then the static content will be serviced by webserver.If its set to true it will be serviced by application server.
Static and dynamic content webserver vs appserver

6.Vertical and horizontal clustering?
 In same machine its vertical if its spanned across different machines its horizontal.How to decide which topology is better.

7.Installation options for websphere application server?
GUI
silent install using response file

8.Datasource creation,messaging configuration?
 Datasource creation websphere




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