I played Call of Duty Modern Warfare 3 during steam free weekends and multiplayer worked fine without any problem.I can't afford to buy games because in my country prices of games are high.I have reloded version of Call of Duty MW 3 and all dlc maps.I registered at FourDeltaOne and made an account and paste LaunchIW5M,DBNetwork.Indigo.dll in game folder.When I click LaunchIW5M it says:

System.net.Webexception:The remote name could not be resloved: 'iw5.prod.founddeltaone.net'

at System.WebClient.DownloadDataInternal(Uri address,WebRequests& request)

at System.WebClient.DownloadString(Uri address)

at System.WebClient.DownloadString(String address)

at DBNUpdater.Updater . . 0...Steam,Directx and.net framework 4 all are up to date and SP is working properly.So tell me guys What can I do to solve this problem?

The remote name could not be resloved: 'iw5.prod.founddeltaone.net'

There's a problem with DNS

Try opening windows command prompt and use this command:

ipconfig /flushdns

Also try restarting your router.

If none of these work, find a way to use another DNS server.