Downgrade iOS 4.3 to iOS 4.2.1

[atiq123]

Step 1: Download the required old ipsw firmware files. (Download links: iOS 4.2.1, iOS 4.1, iOS 4.0.2, iOS 4.0.1)
Step 2: Put your device into DFU mode (not recovery mode).

• Connect your iOS device to your computer.
• Turn it off.
• Start iTunes.
• Hold Power and Home buttons together for 10 seconds or so.
• Release Power button but keep holding the Home button until your computer recognizes a new USB device.
• iTunes will now recognize your iPhone, iPad or iPod touch.

Note: Your iPhone, iPad or iPod touch screen at this time should be blank (black in color), if not, then you are most likely in Recovery Mode, not DFU mode.
Step 3: Now trick iTunes into thinking that it is watching Apple servers, while in real, we are going to change the address to Saurik’s server. To do this:

• Navigate to C:\Windows\System32\drivers\etc\ and locate “hosts” file and delete every thing and past read text in host file before this kindly backup hostfile.

# Copyright (c) 1993-1999 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
127.0.0.1 localhost
::1 localhost
74.208.105.171 gs.apple.com

Restore Custom_ FW iPhone2,1_4.2.1_8C148a4.2.1Custom_Restore
firmware has been successfully Downgrade iOS 4.3 to iOS 4.2.1!!!!!