Selecting correct offline update file for iPad 2 I can't download from the update of my iPad 2 through iTunes. My internet connection is unstable. iTunes is giving me a hard time.

So, I googled around a bit and stumbled on this website, iClarified which allows me to download the *.ipsw files, with resume capability. Ok, found it. 

Please let make some noise if I shouldn't download form this website.

Now, the issue is there are several updates for my iPad2.For the latest 5.1, I have 4 updates files to choose from,


5.1.0 (iPad 2 Wi-Fi): iPad2,1_5.1_9B176_Restore.ipsw
5.1.0 (iPad 2 GSM): iPad2,2_5.1_9B176_Restore.ipsw
5.1.0 (iPad 2 CDMA): iPad2,3_5.1_9B176_Restore.ipsw
5.1.0 (iPad 2 Unknown): iPad2,4_5.1_9B176_Restore.ipsw


Now, I am not sure, which one is for me. 

My iPad is with Wifi and I am under GSM network. So, with this, either update #1 or update #2 is for me. As every iPad comes with wifi, so I am assuming the update #2 is correct for my phone.

Is all my deduction correct? I really want to think twice before messing with it.
iClarified just links to IPSW files hosted by Apple (note the apple.com URLs), so it's a reasonable place to find links to download these files.

Yes, #2 sounds like the correct choice for you. (Note that if you choose the wrong IPSW, iTunes will just give you an error message and not restore the device to it. And even if you could theoretically restore to the wrong IPSW, you can always start over and restore it again.)