nslookup for multiple servers with a single click.

Nslookup is a command testing and troubleshooting the DNS servers. 

Nslookup can be run in two methods.They are interactive and noninteractive. Noninteractive mode is useful when only a single piece of data n eeds to be returned. 

Syntax: nslookup [-option] [hostname] [server]

some times it may need to get the dns details for the large number of servers at that time we need to run the command multiple times and capture the values each and time we hit the command.

To simplify this situation i have found an interesting too named as dnsdataview tool.
You can nslookup multiple number of servers at a single click with the clean GUI.

Download the tool here:

http://www.nirsoft.net/utils/dnsdataview.zip

Reference: http://www.nirsoft.net/utils/dns_records_viewer.html

WHAT IS A REVERSE PROXY SERVER?

A proxy server is a go-between or intermediary server that forwards requests for content from multiple clients to different servers across the Internet. A reverse proxy  server is a type of proxy server that typically sits behind the firewall in a private network and directs client requests to the appropriate back-end server. A reverse proxy provides an additional level of abstraction and control to ensure the smooth flow of network traffic between clients and servers.

Reverse proxy server benefits:

1.Load balancing: A reverse proxy server can act as a “traffic cop,” sitting in front of your back-end servers and distributing client requests across a group of servers in a manner that maximizes speed and capacity utilization while ensuring no one server is overloaded, which can degrade performance. If a server goes down, the load balancer redirects traffic to the remaining online servers.

2.Web acceleration:Reverse proxies can compress inbound and outbound data, as well as cache commonly requested content, both of which speed up the flow of traffic between clients and servers. They can also perform additional tasks such as SSL encryption to take load off of your web servers, thereby boosting their performance.

3.Security and anonymity :By intercepting requests headed for your back-end servers, a reverse proxy server protects their identities and acts as an additional defense against security attacks. It also ensures that multiple servers can be accessed from a single record locater or URL regardless of the structure of your local area network

SSL received a weak ephemeral Diffie-Hellman key. (Error code: ssl_error_weak_server_ephemeral_dh_key) resolved

while recording any application with the load runner,or some times running in to manually we may get the below error in mozilla firefox.

Secure Connection Failed
An error occurred during a connection to consoleeset.soges-tech.ca:8443. SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message. (Error code: ssl_error_weak_server_ephemeral_dh_key)
The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem.

Solution for the above problem:

• Type about:config in the address bar of mozilla firefox
• search for security.ssl3.dhe_rsa_aes_128_sha and security.ssl3.dhe_rsa_aes_256_sha
• Set them both to false by double clicking on it

How can we handle captcha in Load Runner?

CAPTCHA (an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart") is a type of challenge-response test used in computing to determine whether or not the user is human. The term was coined in 2003 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford.

The purpose of the CAPTCHA is to defeat the automation. CAPTCHA are based upon the turning test and as such the main purpose is to differentiate human from machine. Pattern recognition, vocal, visual (dynamic/static) has been broken several time. Much of the time it become a pain for the end-user, because they are a pain to decipher. Cultural reference or social pattern could be proven useful, achieve the same purpose and be less annoying for your customer

If you want to script the application which has CAPTCHA with the load runner you have to get the below things from the DEV.

• To disable CAPTCHA validation
• To make the CAPTCHA as static
• To remove the CAPTCHA
• To send the CAPTCHA value in server response(So that you can correlate)
• Provide the CAPTCHA details which are comes in the data base sequentia

Error "An Authentication object was not found in the SecurityContext" in load runne

while replaying the script you get the error An Authentication object was not found in the Security Context

The reason for the SOAP fault is: 

"An Authentication object was not found in the SecurityContext"

As mentioned by above error, the application  is mostly launched via a web-link where the run time jars / dlls are downloaded locally and application is launched. During launching itself the application takes the credentials from local system (your AD account details) and authenticates the user. In case of replaying this operation in VUGen this authentication information is not available, this can be done by sending the authentication information in the header before the first web-service request as shown below:




Otherwise if your web service method has property for sending authentication object then you can do so in the request itself.

CPU of Load Generator Exceeded 80%

Recently i ran in to a load test and i saw the CPU of Load Generator Exceeded 80% and here are the ways to find out the root cause:

There could be several things, but using 2008 machines on VMs is common. If you are using web vusers should be a small footprint. 

• Check if you have admin rights on the system or not?
• Is CPU consumption above 80% during the entirety of the test
• Check for any mismatch in versions in patch version
• Try to run the agent using "Run as administrator"
• Check for the mdrv process in the htask manager of the controller and the load generator machines while running the test
• make sure to have the same patches level on every component, having a version mix is a real problem.
• Please check if you have the following components installed on your LG machine McAfee Antivirus or  Symantec NetBackup

"Error -27778: SSL protocol error when attempting to connect with host" in load runner

Recently i had some issues with SSL protocol error,while running the scripts in controller i am facing the "Error -27778: SSL protocol error when attempting to connect with host",so finally i got rid of that by using the below steps in the script

Keep the below code at the start of of script

use web_set_sockets_option("SSL_VERSION", "TLS");
    web_set_sockets_option("SSL_VERSION", "1"); 

This forces the SSL connection to the server to use version 1 of the SSL protocol rather than letting the server suggest a version during the connection handshake.

We had same issue on vugen 11.50 with new patch also then  we enabled the below setting
Run-Time Settings -> Preferences -> Select "WinInet Replay Engine instead of Sockets (Windows Only)."

HttpSendRequest" failed, Windows error code=12002 - Perf Center Error_load runner error

While running an internal application using the load runner Controller i was getting the "HttpSendRequest" failed, Windows error code=12002 - Perf Center Error .I solved these by following the below steps:

1.Check Vugen runs script as a process or running  vusers asa  thread?

You can check this in Run time settings-General-Miscellaneous-Multithreading then uncheck the value

2.Are you working with WinInet, and the error itself comes from WinInet API not specifically Vugen.We can see in part of the replay  errors comes from resources during the replay where they were timed out.

If we are forced to use WinInet then this will occur, but if you can use Sockets you may want to try that option instead or a Click and Script protocol.

you can uncheck the WinInet replay instead of sockets (Windows only) in the runtime settings-preferences.This will solve the problem.

3.And the another option is to use web_set_max_retries ("X") to increase the limit of 30 sec.You can place this before the action which is failing but  I wouldn't recommend that.

HttpSendRequest time out only occurres when any transaction takes more than 30 sec to connect to server. This default 30 sec time is because of the use of WinInet Replay engine. Thus this error pops up when you are running script with winInet replay and transactions are taking more than 30 sec. Only thing to get rid of this error is to fine tune the whole system and check the backend and servers to see any request que has formed up.

How to run Performance Center in Professional mode WAN Emulation

Today i will explain about the *.NTX file located on a shared location here.

In the Performance Center the default setting hides the option to use an *.NTX file from a shared f]]location in Professional mode. This can be downloaded from a VE Desktop server.

Here is the process :The shared drive must be accessible to the Controller machines.

• Go to Performance Center user site and create a new test for the load test.Then go to the Workload tab. All the Load Generators should be defined before starting the load test.
• Click the WAN Emulation Settings and select the load generator from the list of LGs.
• Enable the WAN Emulation check-box and the go to WAN Emulation Settings .
• go to Additional Settings
• Enable the Professional mode includes opening files located on a shared drive check-box
• Click OK
• Select the Professional radio-button
• Click the Browse button and locate the NTX file to be used for that Load Generator
• Then click OK

Shared data files usage in Performance Center

In the Performance center, the additional include files get pushed to load generators is to add them to the script in Vugen. This can be accomplished in Vugen by going to the File menu and selecting "Add to script." Any files you select will be added to the action navigation pane in Vugen and will be automatically pushed to any load generators during a test. You should not have to map any directories on the load generators .

If you are using a shared file (such as a function header) that you do not want to attach to all scripts, just make sure that the directory linked to in the script is accessible on all load generators. If not, the appropriate mappings must be completed so the file is accessible during test runs.The file must be placed on the all the load generators which are used in the test