I was helping out one of my friend in installation of Exchange Server 2010 SP2 in existing exchange 2003 environment.

Environment:
2 Domain Controller
Exchange Server 2003 SP2
Exchange Server 2010
Exchange Server 2010 on domain controller

After installing all the prerequisite for windows and completing the active directory switches which are
Setup.com /pl, Setup.com /ps, Setup.com /preparead and Setup.com /preparedomain we started the exchange installation and readiness check failed with error.

Client Access Role Prerequisites
Failed
Error:
The nominated Exchange server for offline address book 'Default Offline Address List' has been deleted. Nominate a valid server and restart setup.
Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=d2b0382e-6f51-46ca-bf12-2dafaa9af2c9


Open Exchange System Manager…>Recipients…>Offline Address List…>Right click properties of Default Offline Address List…Click brows on Offline address list server and select the running exchange 2003 server in the environment.

After changing the server, started the installation and it completed successfully.
I read on the internet regarding the same issue and found that people suggesting that you should delete Default Offline Address Book (List) from adsiedit.msc which is not correct.

If you delete Default Offline Address Book (List) and run the setup again than you will get error saying, Default Offline Address Book cannot be found.


Cheers,