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                                                                    Exhibit 99.4

                                   MEMORANDUM



TO:               Holder of Internet MiddleWare Corporation Non-Qualified Stock
                  Options

FROM:             Network Appliance, Inc.

DATE:             March 17, 1997

RE:               Assumption of Stock Options


                  As you know, Internet MiddleWare Corporation ("Internet
MiddleWare") was recently acquired by Network Appliance, Inc. ("Network
Appliance") through a merger effected on March 17, 1997 (the "Merger").

                  In connection with this transaction, Network Appliance has
assumed all of your outstanding Internet MiddleWare stock options so that those
options now cover shares of Network Appliance common stock. Several additional
changes to your options were also made as part of the assumption process. These
changes are set forth in the Stock Option Assumption Agreement attached hereto
and may be summarized as follows:

                  5.13 The number of shares of Network Appliance common stock
         subject to your option reflects the ratio at which shares of Internet
         MiddleWare common stock were exchanged for shares of Network Appliance
         common stock in the Merger. That ratio was 0.0345267 of a share of
         Network Appliance common stock for each share of Internet MiddleWare
         common stock (the "Exchange Ratio"). Accordingly, the number of Network
         Appliance shares now subject to your option is equal to the number of
         shares of Internet MiddleWare common stock which were subject to your
         option immediately before the Merger, multiplied by the Exchange Ratio
         and rounded down to the next whole share.

                  5.14 The aggregate exercise price payable for the shares of
         Network Appliance common stock now subject to your option is the same
         as the price that was in effect for the shares of Internet MiddleWare
         common stock purchasable under your option immediately prior to the
         Merger. However, the exercise price per share has been adjusted to
         reflect the Exchange Ratio. Accordingly, the exercise price per share
         in effect under your option immediately before the Merger has been
         divided by 0.0345267 to establish the price per share payable for the
         Network Appliance common stock.
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                  3. No change has been made to the vesting schedule in effect
         for your option. Your Network Appliance option will continue to vest in
         accordance with the same installment vesting schedule in effect under
         your Internet MiddleWare option, with the number of Network Appliance
         shares subject to each such installment adjusted to reflect the
         Exchange Ratio. However, you will now earn vesting credit not only for
         the period you continue in employment or service with Internet
         MiddleWare after the Merger but also for any period of service you may
         complete as an employee of Network Appliance or any other Network
         Appliance subsidiary should you subsequently transfer within the
         Network Appliance organization.

                  Attached are two copies of the Stock Option Assumption
Agreement pursuant to which Network Appliance has assumed your Internet
MiddleWare options with the adjustments discussed above. Please review the
agreement carefully so that you understand your rights to acquire Network
Appliance shares. You should contact Jenny Wampler at Network Appliance at (408)
367-3764 if you have any questions. After you have reviewed the agreement,
please sign one copy and return it to Ms. Wampler in the pre-addressed envelope
enclosed.

                  The other copy of the Stock Option Assumption Agreement should
be attached to your existing option documentation so that you will have a
complete record of all the terms and provisions applicable to your option as now
assumed by Network Appliance.


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