POWER OF ATTORNEY

The undersigned, as a Section 16 reporting person of Palo Alto Networks Inc.
(the "Company"), hereby constitutes and appoints Jeff True and Sonia Sexton, the
undersigned's true and lawful attorneys-in-fact to:

        1.      complete and execute Forms 3, 4 and 5 and other forms and all
                amendments thereto as such attorneys-in-fact shall in their
                discretion determine to be required or advisable pursuant to
                Section 16 of the Securities Exchange Act of 1934 (as amended)
                and the rules and regulations promulgated thereunder, or any
                successor laws and regulations, as a consequence of the
                undersigned's ownership, acquisition or disposition of
                securities of the Company; and

        2.      do all acts necessary in order to file such forms with the
                Securities and Exchange Commission, any securities exchange or
                national association, the Company and such other person or
                agency as the attorneys-in-fact shall deem appropriate.

        The undersigned hereby ratifies and confirms all that said
attorneys-in-fact and agent shall do or cause to be done by virtue hereof. The
undersigned acknowledges that the foregoing attorneys-in-fact, in serving in
such capacity at the request of the undersigned, is not assuming, nor is the
Company assuming, any of the undersigned's responsibilities to co mply with
Section 16 of the Securities Exchange Act of 1934 (as amended).

        This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
Company and the foregoing attorneys-in-fact.

        IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 13th day of July, 2012.

                                        Greylock XI GP Limited Partnership

                                        Signature: /s/ Donald A. Sullivan
                                                   ----------------------------
                                                    Donald A. Sullivan

                                        Title: Administrative Partner
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