Before getting in to the business let us clear some tech jargons. Before understanding the purposes of Recovery Mode & DFU Mode you should understand about iBoot. iBoot is the bootloader on iPhone OS devices. During a restore while iPhone is in Recovery Mode, iBoot makes sure that you are flashing a firmware version greater than or equal to a current one. If you are not, iBoot will not allow the restore to proceed. Because of this, firmware downgrading must be done in DFU mode. In easy words if your iPhone is currently running on firmware 2.2.1 iBoot allows only 2.2.1 or 3.0 firmware to flash your iPhone revision.
Recovery Mode : Recovery Mode is a state of iBoot that is used during standard upgrades and restores. As iBoot is active, it does not allow you to downgrade your device’s software. Also, unless it is ‘pwned,’ it will not allow custom firmware to be flashed.
How to put iPhone in to Recovery Mode :
- Make sure you have the latest version of iTunes.
- Turn your iPhone off by holding the power button down until you see “slide to power off”.
- Now press and hold the Home button while reconnecting the USB cable to your iPhone. After iPhone is connected it should power on the device.
- Continue holding the Home button, you will see the iTunes logo appear and then finally a “Connect to iTunes” will be displayed, now is the time to release the Home button. You will then see the following image in to your iTunes Message box.
DFU Mode : DFU Mode is a special mode where the device can still interface with iTunes, yet it does not load the iBoot. The screen will appear totally black in DFU mode, so you can’t guess whether the device is in DFU or powered down from simply looking at the screen. Because iBoot and the OS are not loaded this exploit makes us able to downgrade your iPhone firmware or upgrade with a custom firmware created by Pwnage tool.
How to put iPhone in to DFU Mode :
- Open iTunes and connect the iPhone to your Mac.
- Press and hold the Home button and the Sleep/Wake button at the same time.
3. After exactly 10 seconds release the Sleep/Wake button. Continue holding the home button until your iTunes pops up a message telling you that it has detected an iPhone in recovery mode.
Conclusion : If you are going for a simple Restore or Upgrade your iPhone use Recovery mode and if you are going for Downgrading or Upgrade with a custom firmware go for DFU Mode.