Exhibit 32.1

                            CERTIFICATION 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, Chief Executive Officer of Network Appliance,
Inc. (the "Company"), pursuant to 18 U.S.C.Section 1350, as created by Section
906 of the Sarbanes-Oxley Act of 2002, hereby certify to my knowledge that:

            (i) the Quarterly Report on Form 10-Q of the Company for the
      quarterly period ended October 31, 2003, as filed with the Securities and
      Exchange Commission (the "Report") fully complies with the requirements of
      Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934, as
      amended; and

            (ii) the information contained in the Report fairly presents, in all
      material respects, the financial condition and results of operations of
      the Company.

Date: December 4, 2003                    /s/ Daniel J. Warmenhoven
                                          -------------------------------------
                                              Daniel J. Warmenhoven
                                              Chief Executive Officer


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

      I, Steven J. Gomo, Senior Vice President of Finance and Chief Financial
Officer of Network Appliance, Inc. (the "Company"), pursuant to 18 U.S.C.Section
1350, as created by Section 906 of the Sarbanes-Oxley Act of 2002, hereby
certify to my knowledge that:

            (i) the Quarterly Report on Form 10-Q of the Company for the
      quarterly period ended October 31, 2003, as filed with the Securities and
      Exchange Commission (the "Report") fully complies with the requirements of
      Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934, as
      amended; and

            (ii) the information contained in the Report fairly presents, in all
      material respects, the financial condition and results of operations of
      the Company.

Date: December 4, 2003                    /s/ Steven J. Gomo
                                          -------------------------------------
                                              Steven J. Gomo
                                              Senior Vice President of Finance
                                                and Chief Financial Officer