NetApp (NTAP) 10-K 2006 FY Annual report

Exhibit 32.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER
PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

     I, Daniel J. Warmenhoven, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Annual Report of Network Appliance, Inc., on Form 10-K for the fiscal year ended April 30, 2006 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended, and that information contained in such Annual Report on Form 10-K fairly presents in all material respects the financial condition and results of operations of Network Appliance, Inc.

/s/ DANIEL J. WARMENHOVEN  

Daniel J. Warmenhoven 

Chief Executive Officer 

Date: July 11, 2006