Some time you really face a problem with you outlook, when it's not updating automatically, even you have updated in Active directory and Exchange server.
And that occurring when replication is not happening with you Exchange and outlook.
then you need to download offline Address book. just follow few steps and your Outlook Address book will update.
1- Open the send and receive group like figure no
2-Download the offline address book.
3-Click on full details and select global Address list and click ok(figure no-2)
4- Process will take some time.
After that close your outlook and open again after that your address book will be updating.