I write Below Guide
Windows, navigate to C:/Windows/System32/drivers/etc/ and find the file thats named hosts
Youll mostly have this line at the bottom of the file:
74.208.105.171 gs.apple.com
Either comment this line out by typing a single # (without the quotes) in front of the line (before 74) or remove the line entirely.
Now, save the hosts file and then try updating your iPhone through iTunes.
In most cases, the error shouldnt pop up now.
this should work. To me, I had my iPhone jailbroken too many times. So thats when TinyUmbrella comes to the rescue.
Fixing iTunes Error 3194 for a Jailbroken iPhone using TinyUmbrella
TinyUmbrella is a cool little software that you probably have heard of already.
Note #1: TinyUmbrella and this method are actually part of the 3194 error fix for downgrading your iOS firmware. But in some cases (like ours), it worked for an update too. Its mostly because we had a jailbroken iPhone that wasnt restored to factory settings. Heres how it works:
Note #2: If you wish to downgrade, youll need to save SHSH blobs either to your local drive or on Cydia. Right now, Cydia has saved SHSH blobs up to iOS 5.1.1; youll need to save the SHSH blobs of your device (and you can use TinyUmbrella for this).
Download the iOS firmware that you wish to upgrade/downgrade your iPhone to. (in our case, we went for iOS 6 from a jailbroken 5.1.1)
Download TinyUmbrella
Connect your iPhone and close iTunes if it pops open automatically.
Open TinyUmbrella and then click on Start TSS Server
Put your iPhone in DFU (Here is a quick guide to do this)
Now, if you are updating your firmware, youll have to click on Shift+Restore (Win) / Option+Restore (Mac) and point it to the iOS ipsw file you downloaded in step 1.
Hopefully, iTunes will restore it to the correct iOS firmware you pointed to and update your iPhone to it.