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                                                                   EXHIBIT 10.20

                                F5 NETWORKS, INC.

                       2000 EMPLOYEE EQUITY INCENTIVE PLAN

                             STOCK OPTION AGREEMENT

        Pursuant to the Stock Option Grant Notice ("Grant Notice") and this
Stock Option Agreement, F5 Networks, Inc. (the "Company") has granted you an
option under its 2000 Employee Equity Incentive Plan (the "Plan") to purchase
the number of shares of the Company's Common Stock indicated in the Grant Notice
at the exercise price indicated in the Grant Notice. Your option is granted in
connection with and in furtherance of the Company's compensatory benefit plan
for the Employees, Directors and Consultants of the Company and its Affiliates.
Defined terms not explicitly defined in this Stock Option Agreement but defined
in the Plan shall have the same definitions as in the Plan.

        The details of your option are as follows:

        1. VESTING. Subject to the limitations contained herein, your option
will vest as provided in the Grant Notice, provided that vesting will cease upon
the termination of your Continuous Service.

        2. NUMBER OF SHARES AND EXERCISE PRICE. The number of shares subject to
your option and your exercise price per share referenced in the Grant Notice may
be adjusted from time to time for Capitalization Adjustments, as provided in the
Plan.

        3. METHOD OF PAYMENT. Payment of the exercise price is due in full upon
exercise of all or any part of your option. You may elect to make payment of the
exercise price in cash or by check or in any other manner PERMITTED BY THE GRANT
NOTICE, which may include one or more of the following if the Company, in its
sole discretion at the time your option is exercised, is then offering such
alternatives:

            (a) Provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in The Wall Street Journal, then pursuant
to a program developed under Regulation T as promulgated by the Federal Reserve
Board which, prior to the issuance of Common Stock, results in either the
receipt of cash (or check) by the Company or the receipt of irrevocable
instructions to pay the aggregate exercise price to the Company from the sales
proceeds (a "cashless exercise").

            (b) Provided that at the time of exercise the Common Stock is
publicly traded and quoted regularly in The Wall Street Journal, then by
delivery of already-owned shares of Common Stock (valued at their Fair Market
Value on the date of exercise) if (i) either you have held the already-owned
shares for the period required to avoid a charge to the Company's reported
earnings (generally six months) or you did not acquire the already-owned shares,
directly or indirectly from the Company, and (ii) you own the already-owned
shares free and


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clear of any liens, claims, encumbrances or security interests. "Delivery" for
these purposes, in the sole discretion of the Company at the time your option is
exercised, shall include delivery to the Company of your attestation of
ownership of such shares of Common Stock in a form approved by the Company.
Notwithstanding the foregoing, your option may not be exercised by tender to the
Company of Common Stock to the extent such tender would constitute a violation
of the provisions of any law, regulation or agreement restricting the redemption
of the Company's stock.

            (c) Provided there has been a change in control described in
subsection 11(c) of the Plan and the surviving corporation or acquiring
corporation refuses to assume your option or to substitute a similar option for
your option, then by authorizing the Company to withhold shares from the shares
of the Common Stock otherwise issuable to you as a result of the exercise of
your option. Notwithstanding the foregoing, your option may not be exercised by
withholding shares of Common Stock to the extent such withholding would
constitute a violation of the provisions of any law, regulation or agreement
restricting the redemption of the Company's stock.

        4. WHOLE SHARES. Your option may only be exercised for whole shares.

        5. SECURITIES LAW COMPLIANCE. Notwithstanding anything to the contrary
contained herein, your option may not be exercised unless the shares issuable
upon exercise of your option are then registered under the Securities Act or, if
such shares are not then so registered, the Company has determined that such
exercise and issuance would be exempt from the registration requirements of the
Securities Act. The exercise of your option must also comply with other
applicable laws and regulations governing the option, and the option may not be
exercised if the Company determines that the exercise would not be in material
compliance with such laws and regulations.

        6. TERM. The term of your option commences on the Date of Grant and
expires upon the EARLIEST of the following:

            (a) three (3) months after the termination of your Continuous
Service for any reason other than death or Disability, provided that if during
any part of such three-month period the option is not exercisable solely because
of the condition set forth in paragraph 5, the option shall not expire until the
earlier of the Expiration Date or until it shall have been exercisable for an
aggregate period of three (3) months after the termination of your Continuous
Service;

            (b) twelve (12) months after the termination of your Continuous
Service due to Disability;

            (c) eighteen (18) months after your death if you die either during
your Continuous Service or within three (3) months after your Continuous Service
terminates for reason other than Cause;

            (d) the Expiration Date indicated in the Grant Notice; or


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            (e) the tenth (10th) anniversary of the Date of Grant.

        If your option is an incentive stock option, note that, to obtain the
federal income tax advantages associated with an "incentive stock option," the
Code requires that at all times beginning on the date of grant of the option and
ending on the day three (3) months before the date of the option's exercise, you
must be an employee of the Company or an Affiliate, except in the event of your
death or your Disability. The Company has provided for extended exercisability
of your option in the event of your death or Disability, but the Company cannot
guarantee that your option will necessarily be treated as an "incentive stock
option" if you continue to provide services to the Company or an Affiliate as a
Consultant or Director after your employment terminates or if you exercise your
option more than three (3) months after the date your employment with the
Company or an Affiliate terminates.

        7. EXERCISE.

            (a) You may exercise the vested portion of your option during its
term by delivering a Notice of Exercise (in a form designated by the Company)
together with the exercise price to the Secretary of the Company, or to such
other person as the Company may designate, during regular business hours,
together with such additional documents as the Company may then require.

            (b) By exercising your option you agree that, as a condition to any
exercise of your option, the Company may require you to enter an arrangement
providing for the payment by you to the Company of any tax withholding
obligation of the Company arising by reason of (1) the exercise of your option
or (2) the disposition of shares acquired upon such exercise.

            (c) If your option is an incentive stock option, by exercising your
option you agree that you will notify the Company in writing within fifteen (15)
days after the date of any disposition of any of the shares of the Common Stock
issued upon exercise of your option that occurs within two (2) years after the
date of your option grant or within one (1) year after such shares of Common
Stock are transferred upon exercise of your option.

        8. TRANSFERABILITY. Your option is not transferable, except by will or
by the laws of descent and distribution, and is exercisable during your life
only by you. Notwithstanding the foregoing, by delivering written notice to the
Company, in a form satisfactory to the Company, you may designate a third party
who, in the event of your death, shall thereafter be entitled to exercise your
option.

        9. OPTION NOT A SERVICE CONTRACT. Your option is not an employment or
service contract, and nothing in your option shall be deemed to create in any
way whatsoever any obligation on your part to continue in the employ of the
Company or an Affiliate, or of the Company or an Affiliate to continue your
employment. In addition, nothing in your option shall obligate the Company or an
Affiliate, their respective shareholders, Boards of Directors, Officers or
Employees to continue any relationship that you might have as a Director or
Consultant for the Company or an Affiliate.


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        10. WITHHOLDING OBLIGATIONS.

            (a) At the time your option is exercised, in whole or in part, or at
any time thereafter as requested by the Company, you hereby authorize
withholding from payroll and any other amounts payable to you, and otherwise
agree to make adequate provision for (including by means of a "cashless
exercise" pursuant to a program developed under Regulation T as promulgated by
the Federal Reserve Board to the extent permitted by the Company), any sums
required to satisfy the federal, state, local and foreign tax withholding
obligations of the Company or an Affiliate, if any, which arise in connection
with your option.

            (b) Your option is not exercisable unless the tax withholding
obligations of the Company and/or any Affiliate are satisfied. Accordingly, you
may not be able to exercise your option when desired even though your option is
vested.

        11. NOTICES. Any notices provided for in your option or the Plan shall
be given in writing and shall be deemed effectively given upon receipt or, in
the case of notices delivered by the Company to you, five (5) days after deposit
in the United States mail, postage prepaid, addressed to you at the last address
you provided to the Company.

        12. GOVERNING PLAN DOCUMENT. Your option is subject to all applicable
provisions of the Plan, which are hereby made a part of your option, and is
further subject to all interpretations, amendments, rules and regulations which
may from time to time be promulgated and adopted pursuant to the Plan. In the
event of any conflict between the provisions of your option and those of the
Plan, the provisions of the Plan shall control.


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