X0306 4 2015-12-09 0 0001078075 NETSCOUT SYSTEMS INC NTCT 0001276013 DONAHUE ROBERT E C/O NETSCOUT SYSTEMS, INC. 310 LITTLETON ROAD WESTFORD MA 01886 1 0 0 0 Restricted Stock Unit 2015-12-09 4 A 0 2594 A Common Stock 2594 2594 D Price is N/A. Date is N/A. All of the Restricted Stock Units vest on the date of the Company's Annual Meeting to occur in 2016, provided that during the period from the date of grant through the date of such Annual Meeting, the reporting person attends at least 75% of the meetings, collectively, of the Board and any committee of the Board of which the reporting person is a member. In the event that the attendance requirements are not met, the Restricted Stock Units will not become vested until 12/9/2018. /s/ Greg Sloan, by Power of Attorney 2015-12-10