LoadRunner Vugen's Run-time Settings > Preferences > Advanced option WinInet replay instead of Sockets (Windows only)

LoadRunner's (LR) default engine is Socket based, which is of course more lighter and scalable than the WinInet engine. However, based on my experience, I have seen few situations where script replay fine only with WinInet engine. This may solve the problem in shorter term, however, may introduce scalability issues in case huge number of virtual users needs to be executed on the involved injectors. Socket mode replay uses an HP proprietary interface to the network card providing a lighter engine that is  scalable for load testing and compatible with both Windows and non-Windows Load Generator machines.


WinInet replay uses the Microsoft WinInet DLL to talk to the network card. The limitations of the WinInet replay engine is that it is not scalable, nor does it support UNIX. In addition, when working with threads, the WinInet engine does not accurately emulate the modem speed and number of connections. However, the WinInet interface is used by Internet Explorer and is optimized to work with this browser. It supports all of the features incorporated into the Internet Explorer, and thus, WinInet replay can resolve some replay errors and may produce faster replay transaction times than using the Sockets mode replay.


Important point to be considered:
Only use the WinInet replay if the load test will run in a completely Windows environment with a relatively low number of Vusers are required to run on each Load Generator.