Performance & Loadrunner testing interview questions

Below are some of the most asked loadrunner interview questions and answers in technical rounds of the interviews for performance tester positions in the QA field.

loadrunner interview questions1. Explain the purpose of load testing?

Load testing is used to verify that the application operates as expected during peak usage periods or when it is utilized by a large amount of simultaneous users or handles a heavy load of transactions.

2. Which LoadRunner protocol is used to record or playback an Oracle 9i application?

Verify which protocol your application is running.  Any of the following protocols support LoadRunner: SMTP, POP, HTTPR, ODBC, COM/DCOM, JDBC Sybase, libPeoplesoft, libOracle, SAP, Baan, Siebel, RTEFT, MICORBA, and Windows sockets

3. Can LoadRunner be used to test non-web based applications such as desktop applications?

LoadRunner can be used for desktop applications. When the VUE generator is started, it allows the tester to select the protocol that should be used. In addition to options for web-based applications, there are options for client/server applications as well.

4. How can you call a WinRunner script from LoadRunner?

a.    First generate a scenario by exchanging the VUser script for a GUI WinRunner script.

b.    Select the Details option from the Host menu.

c.    Select the check box for GUI WinRunner.

d.    Finally, execute the scenario.


5. What are the steps to performing stress testing?

The steps to performing stress testing are the following:

1.    Identify testing objectives

2.    Identify scenarios

3.    Identify workload

4.    Identify metrics

5.    Create test cases

6.    Simulate load

7.    Analyze results


6. Define concurrent load.

Concurrent load is a load of Vusers that will be logged into the system or application simultaneously in order to put stress on the server.


7. Explain correlation.

Correlation is a process in LoadRunner that is used to handle dynamic values.  It shows how much (if at all) data is related.


8. What is important in planning a test?

It is important to develop a clearly defined test plan to be certain that the test scenarios that are developed will accomplish all of the test objectives.

9. How do you setup LoadRunner to allow the host and the controller to communicate with each other?

Enable the agent and the remote launcher on the host machine.

10. What type of environment is used for load testing?

Load testing is performed in a controlled environment based on requirement specifications.  A test plan is created from the requirements and scenarios are created based on the test plan.

11. What is used to measure performance?

Transactions are considered to be the only way measuring performance.

12. Define run-time setting.

Loop, log, and time information is included in run-time setting.

13. When should LoadRunner be used?

LoadRunner should be used when many users work simultaneously.

Junior Loadrunner Interview questions

14. What protocols are supported by LoadRunner?

LoadRunner supports standard protocols for the industry such as ODBC and HTTP as well as any other protocol that communicates over a windows socket.

15. Why is a Vuser script created?

The Vuser script is created to simulate the action that a virtual user will perform when executing a scenario.

16. How can a rendezvous point be used?

A rendezvous point is used to simulate the peak server load.

17. What is the purpose of LoadRunner?

The purpose of LoadRunner is to accurately measure and analyze the performance and functionality of a system.

18. Explain what LoadRunner is capable of monitoring.

LoadRunner is capable of monitoring CPU utilization, response of the system, system stress, etc.

19. Explain the different types of correlation.

There are two types of correlation: manual and automatic.  In manual correlation, the data is scanned for values that can be correlated and a value is selected from the list.  In automatic correlation, more rules are set.  This can be specific based on the application server and values are replaced with data.

20. What correlation function is available in LoadRunner?

Wdiff is a LoadRunner tool that can be user to determine dynamic data that can be correlated. Another tool is web_reg_save_param, which can be used to locate and save instances of text strings.


Senior Loadrunner expert Interview questions


21. How is correlation performed?

a.    Determine values that will be correlated

b.    Determine the upper and lower boundaries of the instances of the value

c.    Use the web_reg_save function to parameterize all instances of the value (and do not forget to include the escape character)

22. Define correlation.

Correlation is identifying and resolving data that is unique for each script run action iteration. Each rerun of the data is different from the original recording and this causes failures.

23. Name some advantages of using LoadRunner for testing.

1. It monitors server and network resources to improve performance.

2. It checks for network and client delays in performance.

3. It automatically records performance during test.

24. Define scenario.

Scenarios describe the events that take place during a session of testing. For example, in a banking application there may be scenarios for withdrawing money or depositing cash.

25. What is a Vuser?

A Vuser is a virtual user in LoadRunner.  It is used in place of the human user.

26. What is a Vuser script?

The Vuser script is the script executed in a scenario by the Vuser.

27. What information is in a Vuser script?

The functions that measure/record the performance of the servers during scenario execution is included in the Vuser script.

28. Define transaction.

A transaction measures the time that it takes the server to respond to user tasks.

29. When should a rendezvous point be inserted?

Rendezvous points should be inserted to simulate a server peak load when several Vusers perform simultaneous tasks.

30. How is the LoadRunner controller used?

The LoadRunner Controller is capable of controlling all of the Vusers and it manages and maintains scenarios.

31. What is the LoadRunner host?

The host is the machine that executes Vuser scripts.

32. How many steps are there in the LoadRunner testing process and what are they?

There are 5 steps in the LoadRunner testing process:

1. Test planning

2. Vuser script creation

3. Scenario creation

4. Scenario execution

5. Test result analysis

Q: what is the file extension for vuser script in load runner

Ans: I know .lrr is the extension of loadrunner result file.!!!???

Typical Loadrunner interview questions

33. How many steps are there in developing a Vuser script and what are they?

There are 5 steps in developing a script:

1. Recording

2. Editing

3. Setting run-time

4. Running in stand-alone mode

5. Incorporating into a scenario

34. How do you create a scenario in LoadRunner?

First, the LoadRunner controller must be installed on the host machine. Then create a list of Vuser scripts that will execute on the host.

35. What is the purpose of the Remote Command Launcher?

The Remote Command Launcher or RCL permits the controller to launch the application on the host.

36. Explain the LoadRunner Agent.

The LoadRunner Agent is the interface between the controller and the host machine.

37. Explain how to load the LoadRunner Agent.

The controller must command the RCL to launch the Agent

38. Name some of the types of LoadRunner Vusers?

Some types of Vusers available in LoadRunner are GUI, RTE, database, DCOME, SAP, Java, Baan, and Peoplesoft.

39. Explain the GUI Vuser.

The GUI Vuser manages the application graphical user interface and is capable of running in the both the MS-Windows and X-Windows environments.

40. What tool is used to test MS-Windows?

WinRunner is used to test MS-Window applications.

41. What tool is used to test X-Windows?

VX-runner and X-runner can be used to test X-Windows applications.

42. What is the purpose of the LoadRunner API function?

The LoadRunner API function allows the Vuser to access the data from the server because the database Vuser cannot operate the client application.

43. Explain how to develop a Vuser script for a database.

A Vuser script can be developed for a database by using a script available in LoadRunner or by recording one with the Vuser script generator (VuGen).

44. What is the purpose of VuGen?

VuGen is used to record a Vuser script.

45. How many sections does a Vuser script for a database contain?

A Vuser script for a database has 3 sections:

Code (assembled in C language)

SQL calls to database

Test Script language (TSL)

46. How would you enhance a basic script?

Adding functions, structure, control flow, rendezvous points, and transaction points can enhance basic scripts.

47. Why is the stand-alone mode used?

Stand-alone mode is used to verify that the script runs correctly.

48. What types of functions are created and inserted into a script by VuGen when it is recorded?

There are two types of functions used for this purpose: LR and protocol functions.

49. What is the purpose of the LR-function?

The LR-function is used to obtain information about the Vuser that is executing in a scenario.

50. What is the purpose of the protocol function?

The protocol function is used to obtain information about the Vuser type.

51. What are the VuGen sections used when creating a Vuser script?

VuGen contains 3 sections:

1.  Vuser-init – Records a server login (start)

2.  Action  – Records the client activity

3.  Vuser-end – Record a server log-off (stop)

This is one of the most important loadrunner interview question that is being asked in the interviews so please read more about vugen and vusers from our forum.

Some more General Loadrunner Interview Questions

52. How does VuGen generate a Vuser script?

VuGen creates a script by recording the activity between the server and the client.

53. What can be inserted when editing a script?

Transaction and rendezvous points can be added while editing scripts.

54. Explain the purpose of the LoadRunner start-transaction and its syntax.

The start-transaction function launches a transaction in a script. The syntax is the following:

lr-start-transaction(“transaction title”).

55. Explain the purpose of the LoadRunner end-transaction and its syntax.

The end-transaction function stops a transaction in a script. The syntax is the following:

lr-end-transaction(“transaction title”, LR-AUTO).

56. What is the syntax related to a rendezvous point?

The syntax for rendezvous points is the following:

lr-rendezvous(“rendezvous name”).

57. Name the elements of the LoadRunner controller.

The Controller has 4 elements: Title bar, Menu bar, Tool bar, and Status bar.

Title bar – Contains the name of the current scenario

Menu bar – Contains the various commands

Tool bar – Contains tools available for testing

Status bar – Contains status information about scenario and results

58. How many icons are there at the bottom of the controller window and what are they?

1.    Host Windows – display list of machines

2.    Script Window – display list of Vuser scripts

3.    Rendezvous Window  – lists of rendezvous points

4.    Transaction Window – display of all transactions

5.    Output Window – display of error/notice messages

59. What is the file extension of scenario files?

The file extension to save the information for scenario files is *.lrs.

60. What is the purpose of scenario wizard?

Scenario wizard is used to create new scenarios.

61. Explain LoadRunner sorting and filtering.

The sorting feature in LoadRunner allows the tester to sort all of the Vusers listed based on their Vuser ID numbers.  Filtering displays the information for items that meet the criteria selected in the filter box.  For example, filtering can be done to display only Vusers that are in a certain state.

62. What information is generated for each host?

There are three pieces of information that is generated by each host: status of the host, type of platform (i.e. Windows, Unix, etc.), and details about the scenario.

63. What are the steps to creating a scenario host list?

There are four steps to creating a scenario host list.  They include the following:

1.    Install the RCL on each machine

2.    Add the host name to the host lists.

3.    Set host attributes for each host.

4.    Select the hosts that will participate in the scenario.

64. How can an attribute be modified?


65. What is determined by the host attributes?

1.    Maximum number of Vusers run by the host

2.    Quota for initialization

3.    Location of the WinRunner configuration file

4.    Location of file during execution

66. How can the maximum number of host Vusers be set?

The maximum number of host Vusers can be modified based on the resources available, scenario needs, and license agreements.

67. What is the initialization quota?

The initialization quota is the number of initialized Vusers a host is capable of handling at a time. This question has been asked in 5 out of 10 loadrunner interviews. So elaborate this loadrunner interview question in the comment section.

68. Where is the WinRunner configuration when the LoadRunner controller opens a WinRunner file?

The WinRunner configuration is in the wrun.ini file.

69. What configuration file is the default for a scenario?

The WinRunner configuration file is the default file that the scenario will be instructed to use.

70. What does a local configuration file do?

A local configuration file instructs the Vuser to use the host’s configuration file.

71. What is the purpose of the path?

The path directs the scenario to a specific location on the network.

72. Where does the host save files during run-time?

During run-time, the host saves files in a temporary location on the local drive of each host.

73. What is in the script list?

The script list has all of the Vuser scripts that can be run.

74. What information is in the script windows for each script on a script list?

The information in script windows is the name of the script, Vuser type, location, and the option of the command line.

75. What is used to modify a Vuser script?

An information dialog box can be used to modify a Vuser script.

76. Why are scenarios run?

Scenarios are executed in order to check the functionality and response time of a system that is under a certain amount of load.

77. What happens when a scenario is run?

When a scenario is run, the controller checks the scenario configuration information, invokes the application, and sends the scripts to the related hosts.  Finally, Vusers begin execution when they are ready.

78. How do your run a scenario?

To run a scenario, open an accessible scenario file. Next, setup the scenario with the desired configuration and select the results directory. Once this is done, the scenario can be run.

79. What are the status changes during initialization of a Vuser?

During initialization the Vuser status goes from DOWN > PENDING > INITILIZAING > READY. If initialization fails however, the status simply changes to ERROR.

80. What does the pause command do?

The pause command changes a Vuser status from RUNNING TO PAUSE.

81. What does the Vuser graph display?

The Vuser graph displays the number of the Vusers that are running scripts during each increment of time in a running scenario. Vusers that are in the running or rendezvous states are displayed but those that are ready, loading, or paused are not.

82. What is in the report viewer?

The report viewer has a report header and tool bar.

83. What information is in the report header?

The report header has general scenario information such as scenario name, start time, end time, results, and scenario duration.

84. What is displayed in the rendezvous graph?

The rendezvous graph displays when Vusers are released from rendezvous points, and the number of Vusers that were released from each point.  It can be used to improve the performance time of transactions.

85. What is displayed in the transactions-per-second graph?

The transactions-per-second graph displays the number of successfully completed transactions performed during each second of scenario execution.

86. What is displayed in the percentile graph?

The percentile graph displays the percentage of transactions that were performed within a specific time period.

87. What is displayed in the transaction performance graph?

The transaction performance graph displays the average transaction performance time during each increment of time in scenario execution.

88. How many users can be simulated with a PC version of LoadRunner?

The number of users that can be simulated depends on the type of license.  There are several different types of licenses available. For a basic license up to 250 users can be simulate.

89. What are the LoadRunner Vuser application components?

The application components that are: web server, client, database or for an additionally business application server.  The web server operates on and through LAN, WAN, or web connection.  The application server operates on client, database server, and business server without the use of web connection.

90. Why is parameterization necessary when performing load testing on a web server and database?

Parameterization is necessary to check several different sets of data records to be more realistic and simulate a variety of groupings of users. Parametrization is a must asked in the list of loadrunner interview questions.

91. What is the purpose of the current system time function?

This main purpose of this function is to return the current system time at any given event/point of time when running LoadRunner scripts. It can be used to report start and end times, and transaction times.

92. In addition to using LoadRunner as a tool, what else do you need to know to perform load testing?

In addition to using tools such as LoadRunner, it is important to know the following when performing load testing:

  • Planning and management aspects of load testing
  • Aspects of gathering requirements, acceptance criteria, profile/mix, etc.
  • General understanding of the protocol that will be used

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