EXHIBIT 4.2 AMENDED AND RESTATED INVESTORS? RIGHTS AGREEMENT

Exhibit 4.2

ARUBA WIRELESS NETWORKS, INC.

AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

Initial Closing: September 6, 2005

Subsequent Closing: September 30, 2005

Second Subsequent Closing: September 30, 2006

TABLE OF CONTENTS

AMENDED AND RESTATED
INVESTORS’ RIGHTS AGREEMENT

          THIS AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT (the “Agreement”) is made as of the 6th day of September, 2005, by and among Aruba Wireless Networks, Inc., a Delaware corporation (the “Company”), and the investors listed on Schedule A hereto, each of which is herein referred to as an “Investor.”

RECITALS

          WHEREAS, certain of the Investors (the “Existing Investors”) hold shares of the Company’s Series A Preferred Stock (the “Series A Preferred Stock”) and/or Series B Preferred Stock (the “Series B Preferred Stock”) and/or Series C Preferred Stock (the “Series C Preferred Stock”) and/or shares of Common Stock issued upon conversion thereof, and possess registration rights, information rights, rights of first offer and other rights pursuant to an Amended and Restated Investors’ Rights Agreement dated as of June 24, 2004 by and among the Company and such Existing Investors (the “Prior Agreement”);

          WHEREAS, the Prior Agreement may be amended, and any provision therein waived, with the consent of the Company and the holders of a majority of the outstanding Registrable Securities (as such term is defined in the Prior Agreement);

          WHEREAS, the Existing Investors as holders of a majority of the outstanding Registrable Securities (as such term is defined in the Prior Agreement) of the Company desire to amend and restate the Prior Agreement and to accept the rights created pursuant hereto in lieu of the rights granted to them under the Prior Agreement; and

          WHEREAS, certain Investors are parties to the Series D Preferred Stock Purchase Agreement of even date herewith by and among the Company and certain of the Investors (the “Series D Agreement”), which provides that as a condition to the closing of the sale of the Series D Preferred Stock (the “Series D Preferred Stock” and, collectively with the Series A Preferred Stock, the Series B Preferred Stock and the Series C Preferred Stock, the “Preferred Stock”), this Agreement must be executed and delivered by such Investors, Existing Investors holding a majority of the outstanding Registrable Securities (as such term is defined in the Prior Agreement) of the Company and the Company.

          NOW, THEREFORE, in consideration of the mutual promises and covenants set forth herein, the Existing Investors and the Company hereby agree that the Prior Agreement shall be superseded and replaced in its entirety by this Agreement, and the parties hereto further agree as follows:

          1. Registration Rights . The Company covenants and agrees as follows:

               1.1 Definitions . For purposes of this Section 1:

                    (a) The term “Act” means the Securities Act of 1933, as amended.

                    (b) The term “Form S-3” means such form under the Act as in effect on the date hereof or any registration form under the Act subsequently adopted by the SEC that permits inclusion or incorporation of substantial information by reference to other documents filed by the Company with the SEC.

                    (c) The term “Holder” means any person owning or having the right to acquire Registrable Securities or any assignee thereof in accordance with Section 1.11 hereof.

                    (d) The term “Initial Offering” means the Company’s first firm commitment underwritten public offering of its Common Stock pursuant to a registration statement on Form S-1 (or any successor registration form) under the Act, with gross offering proceeds of not less than $20,000,000 in the aggregate.

                    (e) The term “1934 Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder.

                    (f) The terms “register,” “registered,” and “registration” refer to a registration effected by preparing and filing a registration statement or similar document in compliance with the Act, and the declaration or ordering of effectiveness of such registration statement or document.

                    (g) The term “Registrable Securities” means (i) the Common Stock issuable or issued upon conversion of the Preferred Stock, and (ii) any Common Stock of the Company issued as (or issuable upon the conversion or exercise of any warrant, right or other security that is issued as) a dividend or other distribution with respect to, or in exchange for, or in replacement of, the shares referenced in (i) above, excluding in all cases, however, any Registrable Securities sold by a person in a transaction in which his rights under this Section 1 are not assigned.

                    (h) The number of shares of “Registrable Securities” outstanding shall be determined by the number of shares of Common Stock outstanding that are, and the number of shares of Common Stock issuable pursuant to then exercisable or convertible securities that are, Registrable Securities.

                    (i) The term “Rule 144” shall mean Rule 144 under the Act.

                    (j) The term “Rule 144(k)” shall mean subsection (k) of Rule 144 under the Act.

                    (k) The term “SEC” shall mean the Securities and Exchange Commission.

               1.2 Request for Registration .

                    (a) Subject to the conditions of this Section 1.2, if the Company shall receive at any time after the earlier of (i) three (3) years after the date of this Agreement or (ii) six (6) months after the effective date of the Initial Offering, a written request

from the Holders of fifty percent (50%) or more of the Registrable Securities then outstanding (for purposes of this Section 1.2, the “Initiating Holders”) that the Company file a registration statement under the Act covering the registration of Registrable Securities with an anticipated aggregate offering price of at least $10,000,000, then the Company shall, within ten (10) days of the receipt thereof, give written notice of such request to all Holders, and subject to the limitations of this Section 1.2, use all commercially reasonable efforts to effect, as soon as practicable, the registration under the Act of all Registrable Securities that the Holders request to be registered in a written request received by the Company within twenty (20) days of the mailing of the Company’s notice pursuant to this Section 1.2(a).

                    (b) If the Initiating Holders intend to distribute the Registrable Securities covered by their request by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to this Section 1.2 and the Company shall include such information in the written notice referred to in Section 1.2(a). In such event the right of any Holder to include its Registrable Securities in such registration shall be conditioned upon such Holder’s participation in such underwriting and the inclusion of such Holder’s Registrable Securities in the underwriting (unless otherwise mutually agreed by a majority in interest of the Initiating Holders and such Holder) to the extent provided herein. All Holders proposing to distribute their securities through such underwriting shall enter into an underwriting agreement in customary form with the underwriter or underwriters selected for such underwriting by the Company (which underwriter or underwriters shall be reasonably acceptable to a majority in interest of the Initiating Holders). Notwithstanding any other provision of this Section 1.2, if the underwriter advises the Company that marketing factors require a limitation of the number of securities underwritten (including Registrable Securities), then the Company shall so advise all Holders of Registrable Securities that would otherwise be underwritten pursuant hereto, and the number of shares that may be included in the underwriting shall be allocated to the Holders of such Registrable Securities on a pro rata basis based on the number of Registrable Securities held by all such Holders (including the Initiating Holders). In no event shall any Registrable Securities be excluded from such underwriting unless all other securities are first excluded. Any Registrable Securities excluded or withdrawn from such underwriting shall be withdrawn from the registration.

                    (c) The Company shall not be required to effect a registration pursuant to this Section 1.2:

                         (i) in any particular jurisdiction in which the Company would be required to execute a general consent to service of process in effecting such registration, unless the Company is already subject to service in such jurisdiction and except as may be required under the Act; or

                         (ii) after the Company has effected two (2) registrations pursuant to this Section 1.2, and such registrations have been declared or ordered effective; or

                         (iii) during the period starting with the date sixty (60) days prior to the Company’s good faith estimate of the date of the filing of, and ending on a date one hundred eighty (180) days following the effective date of, a Company-initiated registration

subject to Section 1.3 below, provided that the Company is actively employing in good faith all commercially reasonable efforts to cause such registration statement to become effective; or

                         (iv) if the Initiating Holders propose to dispose of Registrable Securities that may be registered on Form S-3 pursuant to Section 1.4 hereof; or

                         (v) if the Company shall furnish to Holders requesting a registration statement pursuant to this Section 1.2, a certificate signed by the Company’s Chief Executive Officer or Chairman of the Board stating that in the good faith judgment of the Board of Directors of the Company, it would be seriously detrimental to the Company and its stockholders for such registration statement to be effected at such time, in which event the Company shall have the right to defer such filing for a period of not more than one hundred twenty (120) days after receipt of the request of the Initiating Holders, provided that such right shall be exercised by the Company not more than once in any twelve (12)-month period.

               1.3 Company Registration .

                    (a) If the Company proposes to register (including for this purpose a registration effected pursuant to Section 1.2 or by the Company for stockholders other than the Holders) any of its stock or other securities under the Act in connection with the public offering of such securities (other than a registration relating solely to the sale of securities to participants in a Company stock plan, a registration relating to a corporate reorganization or transaction under Rule 145 of the Act, a registration on any form that does not include substantially the same information as would be required to be included in a registration statement covering the sale of the Registrable Securities, or a registration in which the only Common Stock being registered is Common Stock issuable upon conversion of debt securities that are also being registered), the Company shall, at such time, promptly give each Holder written notice of such registration. Upon the written request of each Holder given within twenty (20) days after mailing of such notice by the Company in accordance with Section 3.5, the Company shall, subject to the provisions of Section 1.3(c), use all commercially reasonable efforts to cause to be registered under the Act all of the Registrable Securities that each such Holder has requested to be registered.

                    (b)  Right to Terminate Registration . The Company shall have the right to terminate or withdraw any registration initiated by it under this Section 1.3 prior to the effectiveness of such registration whether or not any Holder has elected to include securities in such registration. The expenses of such withdrawn registration shall be borne by the Company in accordance with Section 1.7 hereof.

                    (c)  Underwriting Requirements . In connection with any offering involving an underwriting of shares of the Company’s capital stock, the Company shall not be required under this Section 1.3 to include any of the Holders’ securities in such underwriting unless they accept the terms of the underwriting as agreed upon between the Company and the underwriters selected by it (or by other persons entitled to select the underwriters) and enter into an underwriting agreement in customary form with such underwriters, and then only in such quantity as the underwriters determine in their sole discretion will not jeopardize the success of the offering by the Company. If the total amount of securities,

including Registrable Securities, requested by stockholders to be included in such offering exceeds the amount of securities sold other than by the Company that the underwriters determine in their sole discretion is compatible with the success of the offering, then the Company shall be required to include in the offering only that number of such securities, including Registrable Securities, that the underwriters determine in their sole discretion will not jeopardize the success of the offering. In no event shall any Registrable Securities be excluded from such offering unless all other stockholders’ securities are first excluded. In the event that the underwriters determine that less than all of the Registrable Securities requested to be registered can be included in such offering, then the Registrable Securities that are included in such offering shall be apportioned pro rata among the selling Holders based on the number of Registrable Securities held by all selling Holders or in such other proportions as shall mutually be agreed to by all such selling Holders. Notwithstanding the foregoing, in no event shall the amount of securities of the selling Holders included in the offering be reduced below twenty-five percent (25%) of the total amount of securities included in such offering, unless such offering is the initial public offering of the Company’s securities, in which case the selling Holders may be excluded if the underwriters make the determination described above and no other stockholder’s securities are included. For purposes of the preceding sentence concerning apportionment, for any selling stockholder that is a Holder of Registrable Securities and that is a venture capital or other investment fund, partnership or corporation, the affiliated venture capital or other investment funds, partners, retired partners and stockholders of such Holder, or the estates and family members of any such partners and retired partners and any trusts for the benefit of any of the foregoing persons shall be deemed to be a single “selling Holder,” and any pro rata reduction with respect to such “selling Holder” shall be based upon the aggregate amount of Registrable Securities owned by all such related entities and individuals.

               1.4 Form S-3 Registration . In case the Company shall receive from the Holders of at least fifty percent (50%) of the Registrable Securities (for purposes of this Section 1.4, the “Initiating Holders”) a written request or requests that the Company effect a registration on Form S-3 and any related qualification or compliance with respect to all or a part of the Registrable Securities owned by such Holder or Holders, the Company shall:

                    (a) promptly give written notice of the proposed registration, and any related qualification or compliance, to all other Holders; and

                    (b) use all commercially reasonable efforts to effect, as soon as practicable, such registration and all such qualifications and compliances as may be so requested and as would permit or facilitate the sale and distribution of all or such portion of such Holders’ Registrable Securities as are specified in such request, together with all or such portion of the Registrable Securities of any other Holders joining in such request as are specified in a written request given within fifteen (15) days after receipt of such written notice from the Company, provided, however, that the Company shall not be obligated to effect any such registration, qualification or compliance, pursuant to this section 1.4:

                         (i) if Form S-3 is not available for such offering by the Holders;

                         (ii) if the Holders, together with the holders of any other securities of the Company entitled to inclusion in such registration, propose to sell Registrable Securities and such other securities (if any) at an aggregate price to the public (net of any underwriters’ discounts or commissions) of less than $3,000,000;

                         (iii) if the Company shall furnish to Holders requesting a registration statement pursuant to this Section 1.4, a certificate signed by the Company’s Chief Executive Officer or Chairman of the Board stating that in the good faith judgment of the Board of Directors of the Company, it would be seriously detrimental to the Company and its stockholders for such registration statement to be effected at such time, in which event the Company shall have the right to defer such filing for a period of not more than one hundred twenty (120) days after receipt of the request of the Initiating Holders, provided that such right shall be exercised by the Company not more than once in any twelve (12)-month period;

                         (iv) if the Company has, within the twelve (12) month period preceding the date of such request, already effected two (2) registrations on Form S-3 for the Holders pursuant to this Section 1.4; or

                         (v) in any particular jurisdiction in which the Company would be required to qualify to do business or to execute a general consent to service of process in effecting such registration, qualification or compliance.

                    (c) If the Initiating Holders intend to distribute the Registrable Securities covered by their request by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to this Section 1.4 and the Company shall include such information in the written notice referred to in Section 1.4(a). The provisions of Section 1.2(b) shall be applicable to such request (with the substitution of Section 1.4 for references to Section 1.2).

                    (d) Subject to the foregoing, the Company shall file a registration statement covering the Registrable Securities and other securities so requested to be registered as soon as practicable after receipt of the request or requests of the Initiating Holders. Registrations effected pursuant to this Section 1.4 shall not be counted as requests for registration or registrations effected pursuant to Sections 1.2 or 1.3, respectively.

               1.5 Obligations of the Company . Whenever required under this Section 1 to effect the registration of any Registrable Securities, the Company shall, as expeditiously as reasonably possible:

                    (a) prepare and file with the SEC a registration statement with respect to such Registrable Securities and use all commercially reasonable efforts to cause such registration statement to become effective, and, upon the request of the Holders of a majority of the Registrable Securities registered thereunder, keep such registration statement effective for a period of up to one hundred twenty (120) days or, if earlier, until the distribution contemplated in the Registration Statement has been completed;

                    (b) prepare and file with the SEC such amendments and supplements to such registration statement and the prospectus used in connection with such

registration statement as may be necessary to comply with the provisions of the Act with respect to the disposition of all securities covered by such registration statement;

                    (c) furnish to the Holders such numbers of copies of a prospectus, including a preliminary prospectus, in conformity with the requirements of the Act, and such other documents as they may reasonably request in order to facilitate the disposition of Registrable Securities owned by them;

                    (d) use all commercially reasonable efforts to register and qualify the securities covered by such registration statement under such other securities or Blue Sky laws of such jurisdictions as shall be reasonably requested by the Holders, provided that the Company shall not be required in connection therewith or as a condition thereto to qualify to do business or to file a general consent to service of process in any such states or jurisdictions;

                    (e) in the event of any underwritten public offering, enter into and perform its obligations under an underwriting agreement, in usual and customary form, with the managing underwriter of such offering;

                    (f) notify each Holder of Registrable Securities covered by such registration statement at any time when a prospectus relating thereto is required to be delivered under the Act of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect, includes an untrue statement of a material fact or omits to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing;

                    (g) cause all such Registrable Securities registered pursuant to this Section 1 to be listed on a national exchange or trading system and on each securities exchange and trading system on which similar securities issued by the Company are then listed;

                    (h) provide a transfer agent and registrar for all Registrable Securities registered pursuant hereunder and a CUSIP number for all such Registrable Securities, in each case not later than the effective date of such registration; and

                    (i) use its best efforts to furnish, at the request of any Holder requesting registration of Registrable Securities pursuant to this Section 1, on the date that such Registrable Securities are delivered to the underwriters for sale in connection with a registration pursuant to this Section 1, if such securities are being sold through underwriters, or if such securities are not being sold through underwriters, on the date that the registration statement with respect to such securities becomes effective, (i) an opinion, dated such date, of the counsel representing the Company for the purposes of such registration, in form and substance as is customarily given to underwriters in an underwritten public offering, addressed to the underwriters and to the Holders requesting registration of Registrable Securities and (ii) a letter dated such date, from the independent certified public accountants of the Company, in form and substance as is customarily given by independent certified public accountants to underwriters in an underwritten public offering and reasonably satisfactory to the Holders of a majority of the Registrable Securities being registered, addressed to the underwriters, if any, and to the Holders requesting registration of Registrable Securities.

          Notwithstanding the provisions of this Section 1, the Company shall be entitled to defer, for a period of one hundred twenty (120) days (but not more than once in any twelve (12) month period), the filing, effectiveness or use of, or trading under, any registration statement if the Company shall determine (and shall provide a certificate of the Company’s Chief Executive Officer confirming such determination) that any such filing or the sale of any securities pursuant to such registration statement would:

                         (i) in the good faith judgment of the Board of Directors of the Company, materially impede, delay or interfere with any material pending or proposed financing, acquisition, corporate reorganization or other similar transaction involving the Company for which the Board of Directors of the Company has authorized negotiations;

                         (ii) in the good faith judgment of the Board of Directors of the Company, materially adversely impair the consummation of any pending or proposed material offering or sale of any class of securities by the Company; or

                         (iii) in the good faith judgment of the Board of Directors of the Company, require disclosure of material nonpublic information that, if disclosed at such time, would be materially harmful to the interests of the Company and its stockholders; provided , however , that during any period referenced in the immediately preceding subsections (i) and (ii) above and this subsection (iii), all executive officers and directors of the Company are also prohibited from selling securities of the Company (or any security of any of the Company’s subsidiaries or affiliates).

          In the event of the suspension of effectiveness of any registration statement pursuant to this Section 1.5, the applicable time period during which such registration statement is to remain effective shall be extended by that number of days equal to the number of days during which the effectiveness of such registration statement was suspended.

          If the Company shall exercise its deferral right under this Section 1.5, such deferral (i) shall be counted for the purposes of determining whether such right has been exercised under Section 1.2(c)(v) during any twelve (12)-month period if such registration was initiated pursuant to Section 1.2 or (ii) shall be counted for the purposes of determining whether such right has been exercised under Section 1.4(b)(iii) during any twelve (12)-month period if such registration was initiated pursuant to Section 1.4. Such deferral right under this Section 1.5 shall not be utilized by the Company during any twelve (12)-month period if a deferral right has already been exercised by the Company pursuant to Section 1.2(c)(v) (during any applicable twelve (12)-month period), provided that such registration was initiated pursuant to Section 1.2. In addition, such deferral right under this Section 1.5 shall not be utilized by the Company during any twelve (12)-month period if a deferral right has already been exercised by the Company pursuant to Section 1.4(b)(iii) (during any applicable twelve (12)-month period), provided that such registration was initiated pursuant to Section 1.4.

               1.6 Information from Holder . It shall be a condition precedent to the obligations of the Company to take any action pursuant to this Section 1 with respect to the Registrable Securities of any selling Holder that such Holder shall furnish to the Company such information regarding itself, the Registrable Securities held by it, and the intended method of

disposition of such securities as shall be reasonably required to effect the registration of such Holder’s Registrable Securities.

               1.7 Expenses of Registration . All0 expenses other than underwriting discounts and commissions incurred in connection with registrations, filings or qualifications pursuant to Sections 1.2, 1.3 and 1.4, including (without limitation) all registration, filing and qualification fees, printers’ and accounting fees, fees and disbursements of counsel for the Company and the reasonable fees and disbursements of one counsel for the selling Holders (not to exceed $25,000) shall be borne by the Company. Notwithstanding the foregoing, the Company shall not be required to pay for any expenses of any registration proceeding begun pursuant to Section 1.2 or Section 1.4 if the registration request is subsequently withdrawn at the request of the Holders of a majority of the Registrable Securities to be registered (in which case all participating Holders shall bear such expenses pro rata based upon the number of Registrable Securities that were to be included in the withdrawn registration), unless, in the case of a registration requested under Section 1.2, the Holders of a majority of the Registrable Securities agree to forfeit their right to one demand registration pursuant to Section 1.2 and provided, however, that if at the time of such withdrawal, the Holders have learned of a material adverse change in the condition, business, or prospects of the Company from that known to the Holders at the time of their request and have withdrawn the request with reasonable promptness following disclosure by the Company of such material adverse change, then the Holders shall not be required to pay any of such expenses and shall retain their rights pursuant to Section 1.2 or 1.4.

               1.8 Delay of Registration . No Holder shall have any right to obtain or seek an injunction restraining or otherwise delaying any such registration as the result of any controversy that might arise with respect to the interpretation or implementation of this Section 1.

               1.9 Indemnification . In the event any Registrable Securities