Mountain Lion : Take an image of OS X joined to a domain
The binding should remain in place when the image is captured.


Boot to your Recovery partition by holding option while powering on your Mac, then selecting Recovery
From the Mac OS X Utilities window choose Disk Utility
In Disk Utility, choose File > New > Disk Image from "Macintosh HD"
You will be asked to name the image (Save As) and select a destination (Where).  Fill in a name and select your external hard drive as the destination.
Once your image is created, which can take a long time depending on how much data is on the Mac, it will appear in the left hand pane of Disk Utility.
Select the image from the left hand pane in Disk Utility and from the menu bar choose Images > Scan Image for Restore.  This will scan the image and append the info for Disk Utility to later restore it to a disk as needed.  This process can take a while as well.


My only concern would be re-binding with the proper computer name if you end up restoring the image to a different Mac, this could be accomplished by editing the Active Directory info in Directory Utility. 


Go to System Preferences > Users &amp; Groups > Login Options and click the Edit button next to Network Accounts.

Click on Open Directory Utility.

Click on the lock in the lower left corner of Directory Utility and enter your password when prompted.
Double click on Active Directory.

You might take a screenshot of your different settings here, under User Experience, Mappings and Administration, just in case they get wiped out and you have to re-enter them.  You can capture a screenshot of this window by pressing commandshift4 and using the cross hairs to grab the part of the screen you'd like to capture.
Click Unbind to unbind from the directory.  Make whatever changes you need and then click Bind to re-bind the Mac to the directory.  When re-binding you'll need to authenticate as an administrator for the corresponding directory.