Apple released iOS 6.1.2 Software Update Fixes an Exchange calendar bug that could result in increased activity on Exchange 2010 Server.

Apple released iOS 6.1.2 Software Update which Fixes an Exchange calendar bug that could result in increased network activity on Exchange Server.

The Bug descripted by Microsoft:
Rapid growth in transaction logs, CPU use, and memory consumption in Exchange Server 2010 when a user syncs a mailbox by using an iOS 6.1 or 6.1.1-based device

Temp Solution:
http://exchangeserverpro.com/block-ios-61-exchange-2010?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+ExchangeServerPro+%28Exchange+Server+Pro%29

Final Solution:

Upgrade to IOS 6.1.2