EXHIBIT 10.1

                                F5 NETWORKS, INC.
                       NONQUALIFIED STOCK OPTION AGREEMENT


         THIS NONQUALIFIED STOCK OPTION AGREEMENT (the "Agreement") is made and
entered into as of October 20, 2003 (the "Grant Date") between F5 Networks,
Inc., a Washington corporation (the "Company") and M. Thomas Hull ("Holder").

         THE PARTIES AGREE AS FOLLOWS:

     1. Grant of Option;  Grant Date. The Company  hereby grants to Holder,  the
right (the  "Option") to purchase up to 225,000  shares of the Company's  Common
Stock  (the  "Option  Shares")  at a price per share of  $23.69  (the  "Exercise
Price"), on the terms and conditions set forth in this Agreement. This Option is
not intended to qualify as an incentive stock option for purposes of Section 422
of the Code.  The number and kind of Option Shares and the Exercise Price may be
adjusted in certain circumstances in accordance with the provisions of Section 9
below.

     2. Definitions.  For purposes of this Agreement,  the following terms shall
be defined as set forth below:

     2.1  Affiliate.  "Affiliate"  means any parent  corporation  or  subsidiary
corporation of the Company, whether now or hereafter existing.

     2.2 Board. "Board" means the Board of Directors of the Company.

     2.3 Code. "Code" means the Internal Revenue Code of 1986, as amended.

     2.4 Common  Stock.  "Common  Stock"  means the common stock of the Company.

     2.5 Continuous  Service.  "Continuous  Service" means that Holder's service
with the Company or an Affiliate,  whether as an employee or consultant,  is not
interrupted or terminated.  Holder's  Continuous  Service shall not be deemed to
have  terminated  merely  because of a change in the  capacity  in which  Holder
renders service to the Company or an Affiliate as an employee or consultant or a
change in the entity for which Holder renders such service,  provided that there
is no interruption or termination of Holder's Continuous Service. For example, a
change in status from an employee of the Company to a consultant of an Affiliate
will not constitute an  interruption  of Continuous  Service.  The Board, in its
sole discretion,  may determine whether  Continuous  Service shall be considered
interrupted in the case of any leave of absence approved by the Board, including
sick leave, military leave or any other personal leave.

     2.6 Disability.  "Disability"  means the permanent and total  disability of
Holder within the meaning of Section 22(e)(3) of the Code.

     2.7   Expiration   Date.   "Expiration   Date"  means   October  19,  2013.

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     2.8 Fair Market Value. "Fair Market Value" means, as of any date, the value
of the Common  Stock.  If the Common  Stock is listed on any  established  stock
exchange or traded on the NASDAQ National Market or the NASDAQ Small Cap Market,
the Fair Market  Value of a share of Common  Stock  shall be the  closing  sales
price for such stock (or the closing  bid, if no sales were  reported) as quoted
on such  exchange or market (or the exchange or market with the greatest  volume
of trading in the Common  Stock) on the day of  determination  or, if the day of
determination  is not a market  trading day, then on the last market trading day
prior to the day of  determination,  as reported  in The Wall Street  Journal or
such other  source as the Board deems  reliable.  In the absence of such markets
for the Common Stock, the Fair Market Value shall be determined in good faith by
the Board.

     2.9 Securities Act.  "Securities  Act" means the Securities Act of 1933, as
amended.

     2.10 Vesting  Commencement  Date.  "Vesting  Commencement  Date" shall mean
Holder's  first day of continuous  service with the Company.

     3. Vesting.  Subject to the limitations  contained herein,  the Option will
vest and become  exercisable  with  respect  to 25% of the Option  Shares on the
first  anniversary  of the  Vesting  Commencement  Date and with  respect to the
remaining  Option  Shares in equal  monthly  installments  over the three  years
following the Vesting  Commencement Date;  provided that vesting will cease upon
the termination of Holder's Continuous Service.

     4. Method of Payment of the Exercise  Price.  Payment of the Exercise Price
is due in full upon exercise of all or any part of the Option.  Holder may elect
to make payment of the Exercise  Price in cash or by check or one or more of the
following  if the  Company,  in its sole  discretion  at the time the  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 Holder has held the already-owned
shares for the period required to avoid a charge to the Company's reported
earnings (generally six months) or Holder did not acquire the already-owned
shares, directly or indirectly from the Company and (ii) Holder owns the
already-owned shares free and clear of any liens, claims, encumbrances or
security interests. "Delivery" for these purposes, in the sole discretion of the
Company at the time the Option is exercised, shall include delivery to the
Company of Holder's attestation of ownership of such shares of Common Stock in a
form approved by the Company. Notwithstanding the foregoing, the 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



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agreement restricting the redemption of the Company's stock.

                  (c) Provided there has been a change in control described in
Section 9(c) and the surviving corporation or acquiring corporation refuses to
assume the Option or to substitute a similar option for the Option, then by
authorizing the Company to withhold shares from the shares of the Common Stock
otherwise issuable to Holder as a result of the exercise of the Option.
Notwithstanding the foregoing, the 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.

     5. Whole Shares. The Option may only be exercised for whole shares.

     6.  Securities  Law  Compliance.  Notwithstanding  anything to the contrary
contained  herein,  the Option may not be exercised  unless the shares  issuable
upon exercise of the 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 the  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.

     7. Term.  The term of the Option  commences  on the Grant Date and  expires
upon the earliest of the following:

                  (a) three (3) months after the termination of Holder's
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 Section 6, 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
Holder's Continuous Service;

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

                  (c) eighteen (18) months after Holder's death if Holder dies
either during Holder's Continuous Service or within three (3) months after
Holder's Continuous Service terminates for reason other than Cause;

                  (d) the Expiration Date; or

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



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     8. Exercise.

                  (a) The vested portion of the Option may be exercised during
its term by delivering a Notice of Exercise in the form attached hereto as
Exhibit A, together with the Exercise Price (payable in the manner set forth in
Section 4) 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. The Option may also be
exercised in such other manner as the Company may designate or authorize.

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

     9. Adjustments Upon Changes in Stock.

                  (a) Capitalization Adjustments. If any change is made in the
Common Stock without the receipt of consideration by the Company (through
merger, consolidation, reorganization, recapitalization, reincorporation, stock
dividend, dividend in property other than cash, stock split, liquidating
dividend, combination of shares, exchange of shares, change in corporate
structure or other transaction not involving the receipt of consideration by the
Company), the number of Option Shares and the Exercise Price will be
appropriately adjusted by the Board, whose determination shall be final, binding
and conclusive. (The conversion of any convertible securities of the Company
shall not be treated as a transaction "without receipt of consideration" by the
Company.)

                  (b) Change in Control--Dissolution or Liquidation. In the
event of a dissolution or liquidation of the Company, the Option shall be
terminated if not exercised (if applicable) prior to such event.

                  (c) Change in Control--Asset Sale, Merger, Consolidation or
Reverse Merger. The Option will immediately vest 100% in the event of a change
in control of the Company consisting of: (1) a sale of substantially all of the
assets of the Company, (2) a merger or consolidation in which the Company is not
the surviving corporation or (3) a reverse merger in which the Company is the
surviving corporation but the shares of Common Stock outstanding immediately
preceding the merger are converted by virtue of the merger into other property,
whether in the form of securities, cash or otherwise.

     10. Transferability.  The Option is not transferable,  except by will or by
the laws of descent and  distribution,  and is exercisable  during Holder's life
only by Holder.  Notwithstanding the foregoing,  by delivering written notice to
the Company, in a form satisfactory to the Company, Holder may designate a third
party who,  in the event of  Holder's  death,  shall  thereafter  be entitled to
exercise the Option.

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     11. Not a Service Contract.  This Agreement is not an employment or service
contract,  and  nothing in this  Agreement  shall be deemed to create in any way
whatsoever  any  obligation  on  Holder's  part to continue in the employ of the
Company, or of the Company to continue Holder's employment. In addition, nothing
in this Agreement shall obligate the Company, its shareholders,  Board, officers
or employees to continue any  relationship  that Holder might have as a director
or consultant for the Company.

     12. Withholding Obligations.

                  (a) At the time the Option is exercised, in whole or in part,
or at any time thereafter as requested by the Company, Holder hereby authorizes
withholding from payroll and any other amounts payable to Holder, and otherwise
agrees 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, which arise in connection with the Option.

                  (b) The Option is not exercisable unless the tax withholding
obligations of the Company are satisfied. Accordingly, Holder may not be able to
exercise the Option when desired even though the Option is vested.

     13. No Rights As A Shareholder.  The Option shall not entitle the Holder to
any cash dividend,  voting or other right of a shareholder  unless and until the
date of issuance of the shares that are the subject of the Option.

     14. Professional  Advice. The acceptance and exercise of the Option and the
sale  of  Option  Shares  has  consequences  under  federal  and  state  tax and
securities  laws which may vary depending upon the individual  circumstances  of
the Holder. Accordingly, Holder acknowledges that he has been advised to consult
his personal  legal and tax advisor in  connection  with this  Agreement and his
dealings  with  respect  to the Option and the  Option  Shares.  Holder  further
acknowledges  that the  Company has made no  warranties  or  representations  to
Holder with respect to the income tax  consequences of the grant and exercise of
the Option or the sale of the Option  Shares and Holder is in no manner  relying
on the Company or its representatives for an assessment of such consequences.

     15.  Assignment;  Binding  Effect.  Subject to the limitations set forth in
this Agreement, this Agreement shall be binding upon and inure to the benefit of
the executors,  administrators,  heirs, legal representatives, and successors of
the  parties  hereto;  provided,  however,  that  Holder  may not  assign any of
Holder's rights under this Agreement.

     16.  Damages.  Holder  shall be  liable  to the  Company  for all costs and
damages,  including  incidental  and  consequential  damages,  resulting  from a
disposition  of Option Shares which is not in conformity  with the provisions of
this Agreement.

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     17.  Governing Law. This  Agreement  shall be governed by, and construed in
accordance  with, the laws of the State of Washington  excluding those laws that
direct the application of the laws of another jurisdiction.

     18.  Notices.  All notices and other  communications  under this  Agreement
shall be in  writing.  Unless  and until  Holder is  notified  in writing to the
contrary, all notices, communications, and documents directed to the Company and
related to the Agreement,  if not delivered by hand, shall be mailed,  addressed
as follows:

                           General Counsel
                           F5 Networks, Inc.
                           401 Elliott Ave West
                           Seattle, WA  98119

Unless and until the Company is notified in writing to the contrary, all
notices, communications, and documents intended for Holder and related to this
Agreement, if not delivered by hand, shall be mailed to Holder's last known
address as shown on the Company's books. Notices and communications shall be
mailed by first class mail, postage prepaid. All mailings and deliveries related
to this Agreement shall be deemed received when actually received, if by hand
delivery, and five (5) business days after mailing, if by mail.

     19.  Amendment of this  Agreement.  The Board at any time, and from time to
time, may amend the terms of this Agreement;  provided, however, that the rights
under this Agreement shall not be impaired by any such amendment  unless (i) the
Company requests the consent of the Holder and (ii) Holder consents in writing.





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         IN WITNESS WHEREOF, the parties have executed this Option Agreement as
of the Effective Date.

                                       F5 NETWORKS, INC.


                                       By
                                           ------------------------------------

                                       Title
                                            -----------------------------------


Holder hereby accepts and agrees to be bound by all of the terms and conditions
of this Agreement.


                                                     --------------------------
                                                     Holder


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                                    EXHIBIT A

                               NOTICE OF EXERCISE

                   (To be signed only upon exercise of Option)


To:      F5 Networks, Inc.
         401 Elliott Ave West
         Seattle, WA  98119


         The undersigned, the holder of an option to purchase shares of common
stock of F5 Networks, Inc. pursuant to an Option Agreement dated as of
__________ __, ____ (the "Option Agreement") hereby irrevocably elects to
exercise the purchase right represented by the Option Agreement for, and to
purchase under that Option Agreement, __________ shares of Common Stock and
herewith makes payment of $_____________ for those shares and payment of
$___________ for holder's share of withholding and employment taxes resulting
from such exercise. Holder hereby confirms the representations, warranties and
agreements set forth in the Option Agreement.

         DATED: __________________, ____.


                                     HOLDER:



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                                     By:
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                                     Title:
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                                     ADDRESS:


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