I've a credit card applicatoin that connects to database on remote server. I have to test how application will works just in case when temporary lost connection. I am unable to disconnect network cable. Will it easy to interrupt temporarily connection and after restore? OS - home windows. Thanks.

In home windows you should use netsh command to disable a network interface. Begin to see the usage in this answer. However I believe this command reacts in a different way based on the OS version...

If it doesn't work maybe try the devcon utility.

The DevCon utility is really a command-line utility that functions being an option to Device Manager. Using DevCon, you are able to enable, disable, restart, update, remove, and query individual products or categories of products. DevCon offers information that's highly relevant to the driver developer and isn't obtainable in Device Manager.

You should use DevCon with Microsoft Home windows 2000, Home windows XP, and Home windows Server 2003. You can't use DevCon with Home windows 95, Home windows 98, or Home windows Millennium Edition.

Use a software firewall for those who have one which blocks certain programs. The Home windows firewall (Win 7 &lifier Vista) has this method.