LoadRunner interview questions
1.What is load testing?
Load testing is to test that if the application works fine with the loads that result from large number of simultaneous users, transactions and to determine weather it can handle peak usage periods.
2.What is Performance testing?
Timing for both read and update transactions should be gathered to determine whether system functions are being performed in an acceptable timeframe. This should be done standalone and then in a multi user environment to determine the effect of multiple transactions on the timing of a single transaction.
3.Explain the Load testing process?
Step 1: Planning the test. Here, we develop a clearly defined test plan to ensure the test scenarios we develop will accomplish load-testing objectives.
Step 2: Creating Vusers. Here, we create Vuser scripts that contain tasks performed by each Vuser, tasks performed by Vusers as a whole, and tasks measured as transactions.
Step 3: Creating the scenario. A scenario describes the events that occur during a testing session. It includes a list of machines, scripts, and Vusers that run during the scenario. We create scenarios using LoadRunner Controller. We can create manual scenarios as well as goal-oriented scenarios. In manual scenarios, we define the number of Vusers, the load generator machines, and percentage of Vusers to be assigned to each script. For web tests, we may create a goal-oriented scenario where we define the goal that our test has to achieve. LoadRunner automatically builds a scenario for us.
Step 4: Running the scenario. We emulate load on the server by instructing multiple Vusers to perform tasks simultaneously. Before the testing, we set the scenario configuration and scheduling. We can run the entire scenario, Vuser groups, or individual Vusers.
Step 5: Monitoring the scenario. We monitor scenario execution using the LoadRunner online runtime, transaction, system resource, Web resource, Web server resource, Web application server resource, database server resource, network delay, streaming media resource, firewall server resource, ERP server resource, and Java performance monitors.
Step 6: Analyzing test results. During scenario execution, LoadRunner records the performance of the application under different loads. We use LoadRunner.s graphs and reports to analyze the application.s performance.
4.When do you do load and performance Testing?
We perform load testing once we are done with interface (GUI) testing. Modern system architectures are large and complex. Whereas single user testing primarily on functionality and user interface of a system component, application testing focuses on performance and reliability of an entire system. For example, a typical application-testing scenario might depict 1000 users logging in simultaneously to a system. This gives rise to issues such as what is the response time of the system, does it crash, will it go with different software applications and platforms, can it hold so many hundreds and thousands of users, etc. This is when we set do load and performance testing.
5.What are the components of LoadRunner?
The components of LoadRunner are The Virtual User Generator, Controller, and the Agent process, LoadRunner Analysis and Monitoring, LoadRunner Books Online.
6.What Component of LoadRunner would you use to record a Script?
The Virtual User Generator (VuGen) component is used to record a script. It enables you to develop Vuser scripts for a variety of application types and communication protocols.
7.What Component of LoadRunner would you use to play Back the script in multi user mode?
The Controller component is used to playback the script in multi-user mode. This is done during a scenario run where a vuser script is executed by a number of vusers in a group.
8.What is a rendezvous point?
You insert rendezvous points into Vuser scripts to emulate heavy user load on the server. Rendezvous points instruct Vusers to wait during test execution for multiple Vusers to arrive at a certain point, in order that they may simultaneously perform a task. For example, to emulate peak load on the bank server, you can insert a rendezvous point instructing 100 Vusers to deposit cash into their accounts at the same time.
9. What is a scenario?
A scenario defines the events that occur during each testing session. For example, a scenario defines and controls the number of users to emulate, the actions to be performed, and the machines on which the virtual users run their emulations.
10.Explain the recording mode for web Vuser script?
We use VuGen to develop a Vuser script by recording a user performing typical business processes on a client application. VuGen creates the script by recording the activity between the client and the server. For example, in web based applications, VuGen monitors the client end of the database and traces all the requests sent to, and received from, the database server. We use VuGen to: Monitor the communication between the application and the server; Generate the required function calls; and Insert the generated function calls into a Vuser script.
11.Why do you create parameters?
Parameters are like script variables. They are used to vary input to the server and to emulate real users. Different sets of data are sent to the server each time the script is run. Better simulate the usage model for more accurate testing from the Controller; one script can emulate many different users on the system.
12.What is correlation? Explain the difference between automatic correlation and manual correlation?
Correlation is used to obtain data which are unique for each run of the script and which are generated by nested queries. Correlation provides the value to avoid errors arising out of duplicate values and also optimizing the code (to avoid nested queries). Automatic correlation is where we set some rules for correlation. It can be application server specific. Here values are replaced by data which are created by these rules. In manual correlation, the value we want to correlate is scanned and create correlation is used to correlate.
13.How do you find out where correlation is required? Give few examples from your projects?
Two ways: First we can scan for correlations, and see the list of values which can be correlated. From this we can pick a value to be correlated. Secondly, we can record two scripts and compare them. We can look up the difference file to see for the values which needed to be correlated. In my project, there was a unique id developed for each customer, it was nothing but Insurance Number, it was generated automatically and it was sequential and this value was unique. I had to correlate this value, in order to avoid errors while running my script. I did using scan for correlation.
14.Where do you set automatic correlation options?
Automatic correlation from web point of view can be set in recording options and correlation tab. Here we can enable correlation for the entire script and choose either issue online messages or offline actions, where we can define rules for that correlation. Automatic correlation for database can be done using show output window and scan for correlation and picking the correlate query tab and choose which query value we want to correlate. If we know the specific value to be correlated, we just do create correlation for the value and specify how the value to be created.
15.What is a function to capture dynamic values in the web Vuser script? -
Web_reg_save_param function saves dynamic data information to a parameter.
16.When do you disable log in Virtual User Generator, When do you choose standard and extended logs?
Once we debug our script and verify that it is functional, we can enable logging for errors only. When we add a script to a scenario, logging is automatically disabled. Standard Log Option: When you select
Standard log, it creates a standard log of functions and messages sent during script execution to use for debugging. Disable this option for large load testing scenarios. When you copy a script to a scenario, logging is automatically disabled Extended Log Option: Select
extended log to create an extended log, including warnings and other messages. Disable this option for large load testing scenarios. When you copy a script to a scenario, logging is automatically disabled. We can specify which additional information should be added to the extended log using the Extended log options.
17.How do you debug a LoadRunner script?
VuGen contains two options to help debug Vuser scripts-the Run Step by Step command and breakpoints. The Debug settings in the Options dialog box allow us to determine the extent of the trace to be performed during scenario execution. The debug information is written to the Output window. We can manually set the message class within your script using the lr_set_debug_message function. This is useful if we want to receive debug information about a small section of the script only.
19.How do you write user defined functions in LR? Give me few functions you wrote in your previous project?
Before we create the User Defined functions we need to create the external
library (DLL) with the function. We add this library to VuGen bin directory. Once the library is added then we assign user defined function as a parameter. The function should have the following format: __declspec (dllexport) char* (char*, char*)Examples of user defined functions are as follows:GetVersion, GetCurrentTime, GetPltform are some of the user defined functions used in my earlier project.
18.What are the changes you can make in run-time settings?
The Run Time Settings that we make are: a) Pacing - It has iteration count. b) Log - Under this we have Disable Logging Standard Log and c) Extended Think Time - In think time we have two options like Ignore think time and Replay think time. d) General - Under general tab we can set the vusers as process or as multithreading and whether each step as a transaction.
19.Where do you set Iteration for Vuser testing?
We set Iterations in the Run Time Settings of the VuGen. The navigation for this is Run time settings, Pacing tab, set number of iterations.
20.How do you perform functional testing under load?
Functionality under load can be tested by running several Vusers concurrently. By increasing the amount of Vusers, we can determine how much load the server can sustain.
21.What is Ramp up? How do you set this?
This option is used to gradually increase the amount of Vusers/load on the server. An initial value is set and a value to wait between intervals can be
specified. To set Ramp Up, go to ‘Scenario Scheduling Options’
22.What is the advantage of running the Vuser as thread?
VuGen provides the facility to use multithreading. This enables more Vusers to be run per generator. If the Vuser is run as a process, the same driver program is loaded into memory for each Vuser, thus taking up a large amount of memory. This limits the number of Vusers that can be run on a single
generator. If the Vuser is run as a thread, only one instance of the driver program is loaded into memory for the given number of
Vusers (say 100). Each thread shares the memory of the parent driver program, thus enabling more Vusers to be run per generator.
23.If you want to stop the execution of your script on error, how do you do that?
The lr_abort function aborts the execution of a Vuser script. It instructs the Vuser to stop executing the Actions section, execute the vuser_end section and end the execution. This function is useful when you need to manually abort a script execution as a result of a specific error condition. When you end a script using this function, the Vuser is assigned the status "Stopped". For this to take effect, we have to first uncheck the .Continue on error. option in Run-Time Settings.
24.What is the relation between Response Time and Throughput?
The Throughput graph shows the amount of data in bytes that the Vusers received from the server in a second. When we compare this with the transaction response time, we will notice that as throughput decreased, the response time also decreased. Similarly, the peak throughput and highest response time would occur approximately at the same time.
25.Explain the Configuration of your systems?
The configuration of our systems refers to that of the client machines on which we run the Vusers. The configuration of any client machine includes its hardware settings, memory, operating system, software applications, development tools, etc. This system component configuration should match with the overall system configuration that would include the network infrastructure, the web server, the database server, and any other components that go with this larger system so as to achieve the load testing objectives.
26.How do you identify the performance bottlenecks?
Performance Bottlenecks can be detected by using monitors. These monitors might be application server monitors, web server monitors, database server monitors and network monitors. They help in finding out the troubled area in our scenario which causes increased response time. The measurements made are usually performance response time, throughput, hits/sec, network delay graphs, etc.
27.If web server, database and Network are all fine where could be the problem?
The problem could be in the system itself or in the application server or in the code written for the application.
28.How did you find web server related issues?
Using Web resource monitors we can find the performance of web servers. Using these monitors we can analyze throughput on the web server, number of hits per second that
occurred during scenario, the number of http responses per second, the number of downloaded pages per second.
29.How did you find database related issues?
By running .Database. monitor and help of .Data Resource Graph. we can find database related issues. E.g. You can specify the resource you want to measure on before running the controller and than you can see database related issues
30.What is the difference between Overlay graph and Correlate graph?
Overlay Graph: It overlay the content of two graphs that shares a common x-axis. Left Y-axis on the merged graph show.s the current graph.s value & Right Y-axis show the value of Y-axis of the graph that was merged. Correlate Graph: Plot the Y-axis of two graphs against each other. The active graph.s Y-axis becomes X-axis of merged graph. Y-axis of the graph that was merged becomes merged graph.s Y-axis.
31.How did you plan the Load? What are the Criteria?
Load test is planned to decide the number of users, what kind of machines we are going to use and from where they are run. It is based on 2 important documents, Task Distribution Diagram and Transaction profile. Task Distribution Diagram gives us the information on number of users for a particular transaction and the time of the load. The peak usage and off-usage are decided from this Diagram. Transaction profile gives us the information about the transactions name and their priority levels with regard to the scenario we are deciding.
32.What does vuser_init action contain?
Vuser_init action contains procedures to login to a server.
33.What does vuser_end action contain?
Vuser_end section contains log off procedures.
34.What is think time? How do you change the threshold?
Think time is the time that a real user waits between actions. Example: When a user receives data from a server, the user may wait several seconds to review the data before responding. This delay is known as the think time. Changing the Threshold: Threshold level is the level below which the recorded think time will be ignored. The default value is five (5) seconds. We can change the think time threshold in the Recording options of the Vugen.
35.What is the difference between standard log and extended log?
The standard log sends a subset of functions and messages sent during script execution to a log. The subset depends on the Vuser type Extended log sends a detailed script execution messages to the output log. This is mainly used during debugging when we want information about: Parameter substitution. Data returned by the server. Advanced trace.
36.Explain the following functions:
lr_debug_message - The lr_debug_message function sends a debug message to the output log when the specified message class is set. lr_output_message - The lr_output_message function sends notifications to the Controller Output window and the Vuser log file. lr_error_message - The lr_error_message function sends an error message to the LoadRunner Output window. lrd_stmt - The lrd_stmt function associates a character string (usually a SQL statement) with a cursor. This function sets a SQL statement to be processed. lrd_fetch - The lrd_fetch function fetches the next row from the result set.
37.Throughput - If the throughput scales upward as time progresses and the number of Vusers increase, this indicates that the bandwidth is sufficient. If the graph were to remain relatively flat as the number of Vusers increased, it would
be reasonable to conclude that the bandwidth is constraining the volume of
data delivered.
38.Types of Goals in Goal-Oriented Scenario
Load Runner provides you with five different types of goals in a goal oriented scenario:
The number of concurrent Vusers
The number of hits per second
The number of transactions per second
The number of pages per minute
The transaction response time that you want your scenario
39.Analysis Scenario (Bottlenecks): In Running Vuser graph correlated with the response time graph you can see that as the number of Vusers increases, the average response time of the check itinerary transaction very gradually increases. In other words, the average response time steadily increases as the load
increases. At 56 Vusers, there is a sudden, sharp increase in the average response
time. We say that the test broke the server. That is the mean time before failure (MTBF). The response time clearly began to degrade when there were more than 56 Vusers running simultaneously.
40.What is correlation? Explain the difference between automatic correlation and manual correlation?
Correlation is used to obtain data which are unique for each run of the script and which are generated by nested queries. Correlation provides the value to avoid errors arising out of duplicate values and also optimizing the code (to avoid nested queries). Automatic correlation is where we set some rules for correlation. It can be application server specific. Here values are replaced by data which are created by these rules. In manual correlation, the value we want to correlate is scanned and create correlation is used to correlate.
41.Where do you set automatic correlation options?
Automatic correlation from web point of view, can be set in recording options and correlation tab. Here we can enable correlation for the entire script and choose either issue online messages or offline actions, where we can define rules for that correlation. Automatic correlation for database, can be done using show output window and scan for correlation and picking the correlate query tab and choose which query value we want to correlate. If we know the specific value to be correlated, we just do create correlation for the value and specify how the value to be created.
42.What is a function to capture dynamic values in the web vuser script?
Web_reg_save_param function saves dynamic data information to a parameter.
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Manual Testing Faqs
1. What is Software Testing?
A. Testing involves operation of a system or application under controlled conditions and evaluating the results,The controlled conditions should include both normal and abnormal conditions.
Testing is a process of executing a program with the intend of finding the errors.
2. What is the Purpose of Testing?
A. The purpose of testing is
1· To uncover hidden errors
2· To achieve the maximum usability of the system
3· To Demonstrate expected performance of the system
3. What types of testing do testers perform?
A. Two types of testing 1.White Box Testing 2.Black Box Testing.
4. What is the Outcome of Testing?
A. The outcome of testing will be a stable application which meets the customer Req's.
5. What kind of testing have you done?
A. Usability,Functionality,System testing,regression testing,UAT
(it depends on the person).
6. What is the need for testing?
A. The Primary need is to match requirements get satisfied with the functionality
and also to answer two questions
1· Whether the system is doing what it supposes to do?
2· Whether the system is not performing what it is not suppose to do?
7. What are the entry criteria for Functionality and Performance testing?
A. Entry criteria for Functionality testing is Functional Specification /BRS (CRS)/User Manual.An integrated application, Stable for testing.
Entry criteria for Performance testing is successfully of functional testing,once all the requirements related to functional are covered and tested, and approved or validated.
8. Why do you go for White box testing, when Black box testing is available?
A. A benchmark that certifies Commercial (Business) aspects and also functional (technical)aspects is objectives of black box testing. Here loops, structures, arrays, conditions,files, etc are very micro level but they arc Basement for any application, So White box takes these things in Macro level and test these things
Even though Black box testing is available,we should go for White box testing also,to check the correctness of code and for integrating the modules.
9.What are the entry criteria for Automation testing?
A. Application should be stable. Clear Design and Flow of the application is needed.
10.When to start and Stop Testing?
A. This can be difficult to determine. Many modern software applications are so complex,and run in such an interdependent environment, that complete testing can never be done.
Common factors in deciding when to stop are:
Deadlines (release deadlines, testing deadlines, etc.)
Test cases completed with certain percentage passed
Test budget depleted
Coverage of code/functionality/requirements reaches a specified point
Bug rate falls below a certain level
Beta or alpha testing period ends
11.What is Quality?
A. It ensures that software is a Bug free,delivered in time,with in budget,meets customer requirements and maintainable.Quality standards are different in various areas like accounting department might define quality in terms of Profit.
12.What is Baseline document?
A. The review and approved document is called as baseline document (i.e)Test plan,SRS.
13.What is verification?
A. To check whether we are developing the right product according to the customer
requirements r not.It is a static process.
14.What is validation?
A. To check whether we have developed the product according to the customer requirements r not.It is a Dynamic process.
15.What is quality assurance?
A. Quality Assurance measures the quality of processes used to create a quality product.
1.It is a system of management activities.
2.It is a preventive process.
3.It applies for entire life cycle.
4.Deals with Proces.
16.What is quality control?
A. Quality control measures the quality of a product
1.It is a specific part of the QA procedure.
2.It is a corrective process.
3.It applies for particular product.
4.Deals with the product.
17.What is SDLC and TDLC?
A. Software development life cycle(SDLC) is life cycle of a project from starting to ending of the project.
1.Requiremnts Specification. 2.Analysis
3.Design 4.Coding
5.Testing 6.User acceptance test(UAT)
7.Maintainance
Software Test Life Cycle(STLC) is a life cycle of the testing process.
1.Requiremnts Specification. 2.Planning
3.Test case Design. 4.Execution
5.Bug Reporting. 6.Maintainance
18.What are the Qualities of a Tester?
A. Tester should have qualities like
1.ability to break 2.paitence 3.communication
4.Presentation 5.team work. 6.negative thinking with good judgment skills
19.What are the various levels of testing?
A. The various levels of testing like
1· Ad - Hoc testing
2. Sanity Test
3. Regression Testing
4. Functional testing
5· Web Testing
20.After completing testing, what would you deliver to the client?
A. It is depend upon what you have specified in the test plan document.
the contents delivers to the clients is nothing but Test Deliverables.
1.Test plan document 2.Master test case document 3.Test summary Report.
4.Defect Reports.
21.What is a Test Bed?
A. Test bed means under what test environment(Hardware,software set up) the
application will run smoothly.
22.Why do you go for Test Bed?
A. We will prepare test bed bcoz first we need to identify under which
environment (Hardware,software) the application will run smoothly,then
only we can run the application smoothly without any intereptions.
23.What is Severity and Priority and who will decide what?
A. Severity and priority will be assigned for a particular bug to know the importance of the bug.
Severity:How sevierly the bug is effecting the application.
Priority:Informing to the developer which bug to be fix first.
24.Can Automation testing replace manual testing? If it so, how?
A. Yes,it can be done manually when the project is small,having more time.
we can test with minimum number of users.
25.What is a test case?
A. A test case is a document that describes an input, action, or event and an expected response, to determine if a feature of an application is working correctly.
26.What is a test condition?
A. The condition required to test a feature.(pre condition)
27.What is the test script?
A. Test script is the script which is generated by an automation tool while recording a application features.
28.What is the test data?
A. Test data means the input data(valid,invalid data) giving to check the feature
of an application is working correctly.
29.What is the difference between Re-testing and Regression testing?
A Re-testing:Executing the same test case by giving the no. of inputs on same build.
Regression testing:Executing the same test case on a modified build.
30.What are the different types of testing techniques?
A. 1.white Box testing 2.Black Box testing.
31.What are the different types of test case techniques?
A. 1.Equilance Partition. 2.Boundary Value Analysis. 3.Error guesing.
32.What ifs the difference between defect, error, bug?
A. Defect:While executing the test case if u found any mismatch,the u will report
it to the development team,that is called defect.
Bug:Once the developer accepts your defect,the it is called as a bug.
error:it may be program error or syntax error.
33.What is the difference between quality and testing?
A. QA is more a preventive thing, ensuring quality in the company and therefore
the product rather than just testing the product for software bugs?
TESTING means "quality control"
Quality control measures the quality of a product
Quality Assurance measures the quality of processes used to create a
quality product.
34.What is the difference between White & Black Box Testing?
A. White Box Testing:Based on the knowledge of the internal logic of an application's code.Tests are based on coverage of code statements, branches, paths, conditions.
Black Box testing:- not based on any knowledge of internal design or code.
Tests are based on requirements and functionality.
35.What is the difference between Quality Assurance and Quality Control?
A.
Quality Assurance measures the quality of processes used to create a
quality product.
Quality control measures the quality of the product.
36.What is the difference between Testing and debugging?
A. The Purpose of testing is to show the program has bugs.
The Purpose of debugging is find the error/ misconception that led to failure and implement program changes that correct the error.
37.What is the difference between bug and defect?
A. Defect:While executing the test case if u found any mismatch,the u will report
it to the development team,that is called defect.
Bug:Once the developer accepts your defect,the it is called as a bug.
38.What is the difference between unit testing and integration testing?
A. Unit Testing:It is a testing activity typically done by the developers not by testers,as it requires detailed knowledge of the internal program design and code. Not always easily done unless the application has a well-designed architecture with tight code.
integration testing:testing of combined parts of an application to determine if they function together correctly. The 'parts' can be code modules, individual applications,client and server applications on a network, etc. This type of testing is especially relevant to client/server and distributed systems.
39. What is the diff between Volume & Load?
A. Load,stress testing comes under performance testing.
Load Testing:To test the performance of the application by gradually
increasing the user loads.
Stress Testing:TO test the performance of the application and to find the server break down or where the server crashes.
Volume Testing:To test whether it can able to send max data according to client req's.
40. What is the Diff between Two Tier & Three tier Architecture?
A. Two Tier Architecture:It is nothing but client server Architecture,where client will hit request directly to server and client will get response directly from server.
Three tier Architecture:It is nothing but Web Based application,here in between client and server middle ware will be there,if client hits a request it will go to the middle ware and middle ware will send to server and vise-versa.
41. What is the diff between Integration & System Testing?
A. integration testing:testing of combined parts of an application to determine if they function together correctly. The 'parts' can be code modules, individual applications,client and server applications on a network, etc. This type of testing is especially relevant to client/server and distributed systems.
System Testing:system testing will conducted on the entire system to check whether
it is meeting the customer requirements r not.
42. What is the diff between walk through and inspection?
A. walk through:A 'walk through' is an informal meeting for evaluation or informational purposes. Little or no preparation is usually required
inspection:Inspection is an formal meeting,here every thing discussed will be documented such as a requirements spec or a test plan, and the purpose is to find problems and see what's missing,The result of the inspection meeting should be a written report.
43. What is the Diff between static and dynamic?
A. Static Testing:Test activities that are performed without running the software is called Static Testing,it includes inspections,walk throughs and desk checks.
dynamic testing:Test activities that are performed by running the software is called dynamic Testing.
44. What is the diff between alpha testing and beta testing?
A. Alpha Testing:alpha testing will be performed by client in our environment with dummy data,In this phase some major bugs can be allowed,later which will be solved by our development team.
beta testing:beta testing will be performed by client in his environment with real data,In this phase no bugs can be allowed.
45.What is Recovery testing?
A.testing how well a system recovers from crashes, hardware failures, or other catastrophic problems.
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