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EXHIBIT 31.2

                                 CERTIFICATIONS

I, Steven B. Coburn, certify that:

1)       I have reviewed this annual report on Form 10-K, as amended, of F5
         Networks, Inc.;

2)       Based on my knowledge, this report does not contain any untrue
         statement of a material fact or omit to state a material fact necessary
         to make the statements made, in light of the circumstances under which
         such statements were made, not misleading with respect to the period
         covered by this report;

3)       Based on my knowledge, the financial statements, and other financial
         information included in this report, fairly present in all material
         respects the financial condition, results of operations and cash flows
         of the registrant as of, and for, the periods presented in this report;

4)       The registrant's other certifying officer and I are responsible for
         establishing and maintaining disclosure controls and procedures (as
         defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the
         registrant and have:

         a)       designed such disclosure controls and procedures, or caused
                  such disclosure controls and procedures to be designed under
                  our supervision, to ensure that material information relating
                  to the registrant, including its consolidated subsidiaries, is
                  made known to us by others within those entities, particularly
                  during the period in which this report is being prepared;

         b)       evaluated the effectiveness of the registrant's disclosure
                  controls and procedures and presented in this report our
                  conclusions about the effectiveness of the disclosure controls
                  and procedures, as of the end of the period covered by this
                  report based on such evaluation; and

         c)       disclosed in this report any change in the registrant's
                  internal controls over financial reporting that occurred
                  during our most recent fiscal quarter that has materially
                  affected, or is reasonably likely to materially affect, the
                  registrant's internal controls over financial reporting; and

5)       The registrant's other certifying officer and I have disclosed, based
         on our most recent evaluation, to the registrant's auditors and the
         audit committee of registrant's board of directors (or persons
         performing the equivalent functions):

         a)       all significant deficiencies in the design or operation of
                  internal controls over financial reporting which are
                  reasonably likely to adversely affect the registrant's ability
                  to record, process, summarize and report financial data; and
                  any fraud, whether or not material, that involves management
                  or other employee who have a significant role in the
                  registrant's internal controls over financial reporting.

    Date: December 6, 2004


                   /s/ STEVEN B. COBURN
          ----------------------------------
                  Steven B. Coburn
                  Senior Vice President, Chief Financial Officer

