NETSCOUT SYSTEMS, INC. AMENDED AND RESTATED 2011 EMPLOYEE STOCK PURCHASE PLAN ADOPTED BY THE BOARD OF DIRECTORS:JUNE 29, 2011 APPROVED BY THESTOCKHOLDERS: SEPTEMBER 7, 2011 AMENDED ANDRESTATED BY THE COMPENSATION COMMITTEE: FEBRUARY 8, 2012

Exhibit 10.1

NETSCOUT SYSTEMS, INC.

AMENDED AND RESTATED 2011 EMPLOYEE STOCK PURCHASE PLAN

ADOPTED BY THE BOARD OF DIRECTORS: JUNE 29, 2011

APPROVED BY THE STOCKHOLDERS: SEPTEMBER 7, 2011

AMENDED AND RESTATED BY THE COMPENSATION COMMITTEE: FEBRUARY 8, 2012

(a) This Plan is intended as the successor to the NetScout Systems, Inc. 1999 Employee Stock Purchase Plan (the “Prior Plan”). Following the Effective Date of this Plan, no additional options to purchase shares of Common Stock shall be granted under the Prior Plan. All Purchase Rights granted on or after the Effective Date of this Plan shall be subject to the terms of this Plan.

(b) The purpose of the Plan is to provide a means by which Eligible Employees of the Company and certain Designated Companies may be given an opportunity to purchase shares of Common Stock. The Plan is intended to permit the Company to grant a series of Purchase Rights to Eligible Employees.

(c) The Company, by means of the Plan, seeks to retain the services of such Employees, to secure and retain the services of new Employees and to provide incentives for such persons to exert maximum efforts for the success of the Company, its Related Corporations and Affiliates.

(d) This Plan includes two components: a 423 Component and a Non-423 Component. It is the intention of the Company to have the 423 Component qualify as an Employee Stock Purchase Plan. The provisions of the 423 Component, accordingly, shall be construed so as to extend and limit participation in a uniform and nondiscriminatory basis consistent with the requirements of Section 423 of the Code. In addition, this Plan authorizes the grant of Purchase Rights under the Non-423 Component that does not qualify as an Employee Stock Purchase Plan; such Purchase Rights shall be granted pursuant to rules, procedures or subplans adopted by the Board designed to achieve tax, securities laws or other objectives for Eligible Employees and the Company, its Related Corporations and Affiliates. Except as otherwise provided herein or determined by the Board, the Non-423 Component will operate and be administered in the same manner as the 423 Component

(e) If a Participant transfers employment from the Company or any Designated Related Corporation participating in the 423 Component to a Designated Affiliate participating in the Non-423 Component, he or she shall immediately cease to participate in the 423 Component; however, any Contributions made for the Purchase Period in which such transfer occurs shall be transferred to the Non-423 Component, and such Participant shall immediately join the then current Offering under the Non-423 Component upon the same terms and conditions in effect for his or her participation in the Plan, except for such modifications as may be required by applicable law. A Participant who transfers employment from a Designated Affiliate participating in the Non-423 Component to the Company or any Designated Related Corporation participating in the 423 Component shall remain a Participant in the Non-423

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Component until the earlier of (i) the end of the current Offering Period under the Non-423 Component, or (ii) the Offering Date of the first Offering in which he or she participates following such transfer.

(a) The Board shall administer the Plan unless and until the Board delegates administration of the Plan to a Committee or Committees, as provided in Section 2(c).

(b) The Board shall have the power, subject to, and within the limitations of, the express provisions of the Plan:

(i) To determine how and when Purchase Rights to purchase shares of Common Stock shall be granted and the provisions of each Offering of such Purchase Rights (which need not be identical), including which Designated Related Corporations and Designated Affiliates shall participate in the 423 Component or the Non-423 Component.

(ii) To designate from time to time which Related Corporations and Affiliates of the Company shall be eligible to participate in the Plan as Designated Related Corporations and Designated Affiliates.

(iii) To construe and interpret the Plan and Purchase Rights, and to establish, amend and revoke rules and regulations for its administration. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan, in a manner and to the extent it shall deem necessary or expedient to make the Plan fully effective.

(iv) To settle all controversies regarding the Plan and Purchase Rights granted under it.

(v) To suspend or terminate the Plan at any time as provided in Section 12.

(vi) To amend the Plan at any time as provided in Section 12.

(vii) Generally, to exercise such powers and to perform such acts as it deems necessary or expedient to promote the best interests of the Company, its Related Corporations and Affiliates and to carry out the intent that the 423 Component be treated as an Employee Stock Purchase Plan.

(viii) To adopt such procedures and sub-plans as are necessary or appropriate to permit participation in the Plan by Employees who are foreign nationals or employed outside the United States. Without limiting the generality of the foregoing, the Board specifically is authorized to adopt rules, procedures and subplans, which, for purposes of the Non-423 Component, may be outside the scope of Section 423 of the Code, regarding, without limitation, eligibility to participate in the Plan, handling and making of Contributions, establishment of bank or trust accounts to hold Contributions, payment of interest, conversion of local currency, obligations to pay payroll tax, determination of beneficiary designation requirements, withholding procedures and handling of share issuances, which may vary according to local requirements.

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(ix) To make any other determination and take any other action that the Board deems necessary or desirable for the administration of the Plan.

(c) The Board may delegate some or all of the administration of the Plan to a Committee or Committees. If administration is delegated to a Committee, the Committee shall have, in connection with the administration of the Plan, the powers theretofore possessed by the Board that have been delegated to the Committee, including the power to delegate to a subcommittee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board shall thereafter be to the Committee or subcommittee), subject, however, to such resolutions, not inconsistent with the provisions of the Plan, as may be adopted from time to time by the Board. The Board may retain the authority to concurrently administer the Plan with the Committee and may, at any time, revest in the Board some or all of the powers previously delegated. Whether or not the Board has delegated administration of the Plan to a Committee, the Board shall have the final power to determine all questions of policy and expediency that may arise in the administration of the Plan.

(d) All determinations, interpretations and constructions made by the Board in good faith shall not be subject to review by any person and shall be final, binding and conclusive on all persons.

(a) Subject to the provisions of Section 11(a) relating to Capitalization Adjustments, the shares of Common Stock that may be sold pursuant to Purchase Rights shall not exceed in the aggregate 2,500,000 shares of Common Stock.

(b) If any Purchase Right granted under the Plan shall for any reason terminate without having been exercised, the shares of Common Stock not purchased under such Purchase Right shall again become available for issuance under the Plan.

(c) The stock purchasable under the Plan shall be shares of authorized but unissued or reacquired Common Stock, including shares repurchased by the Company on the open market.

(a) The Board may from time to time grant or provide for the grant of Purchase Rights to purchase shares of Common Stock under the Plan to Eligible Employees in an Offering (consisting of one or more Purchase Periods) on an Offering Date or Offering Dates selected by the Board. Each Offering shall be in such form and shall contain such terms and conditions as the Board shall deem appropriate, and with respect to the 423 Component shall comply with the requirement of Section 423(b)(5) of the Code that all Employees granted Purchase Rights shall have the same rights and privileges. The terms and conditions of an Offering shall be incorporated by reference into the Plan and treated as part of the Plan. The provisions of separate Offerings need not be identical, but each Offering shall include (through incorporation of the provisions of this Plan by reference in the document comprising the Offering or otherwise) the period during which the Offering shall be effective, which period shall not exceed 27 months beginning with the Offering Date, and the substance of the provisions contained in Sections 5 through 8, inclusive.

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(b) If a Participant has more than one Purchase Right outstanding under the Plan, unless he or she otherwise indicates in agreements or notices delivered hereunder: (i) each agreement or notice delivered by that Participant shall be deemed to apply to all of his or her Purchase Rights under the Plan, and (ii) a Purchase Right with a lower exercise price (or an earlier-granted Purchase Right, if different Purchase Rights have identical exercise prices) shall be exercised to the fullest possible extent before a Purchase Right with a higher exercise price (or a later-granted Purchase Right if different Purchase Rights have identical exercise prices) shall be exercised.

(c) The Board shall have the discretion to structure an Offering so that if the Fair Market Value of a share of Common Stock on the first day of a new Purchase Period within that Offering is less than or equal to the Fair Market Value of a share of Common Stock on the Offering Date for that Offering, then (i) that Offering shall terminate immediately, and (ii) the Participants in such terminated Offering shall be automatically enrolled in a new Offering beginning on the first day of such new Purchase Period.

(a) Purchase Rights may be granted only to Employees of the Company or, as the Board may designate as provided in Section 2(b), to Employees of a Related Corporation or Affiliate. Except as provided in Section 5(b), an Employee shall not be eligible to be granted Purchase Rights under the Plan unless, on the Offering Date, such Employee has been in the employ of the Company, the Related Corporation or the Affiliate, as the case may be, for such continuous period preceding such Offering Date as the Board may require, but in no event shall the required period of continuous employment be greater than two years. In addition, the Board may provide that no Employee shall be eligible to be granted Purchase Rights under the Plan unless, on the Offering Date, such Employee’s customary employment with the Company or the Related Corporation or the Affiliate is more than 20 hours per week and more than five months per calendar year for purposes of the 423 Component or such other criteria as the Board may determine consistent with Section 423 of the Code.

(b) The Board may provide that each person who, during the course of an Offering, first becomes an Eligible Employee shall, on a date or dates specified in the Offering which coincides with the day on which such person becomes an Eligible Employee or which occurs thereafter, receive a Purchase Right under that Offering, which Purchase Right shall thereafter be deemed to be a part of that Offering. Such Purchase Right shall have the same characteristics as any Purchase Rights originally granted under that Offering, as described herein, except that:

(i) the date on which such Purchase Right is granted shall be the “Offering Date” of such Purchase Right for all purposes, including determination of the exercise price of such Purchase Right;

(ii) the period of the Offering with respect to such Purchase Right shall begin on its Offering Date and end coincident with the end of such Offering; and

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(iii) the Board may provide that if such person first becomes an Eligible Employee within a specified period of time before the end of the Offering, he or she shall not receive any Purchase Right under that Offering.

(c) No Employee shall be eligible for the grant of any Purchase Rights under the 423 Component if, immediately after any such Purchase Rights are granted, such Employee owns stock possessing 5% or more of the total combined voting power or value of all classes of stock of the Company or of any Related Corporation. For purposes of this Section 5(c), the rules of Section 424(d) of the Code shall apply in determining the stock ownership of any Employee, and stock which such Employee may purchase under all outstanding Purchase Rights and options shall be treated as stock owned by such Employee.

(d) As specified by Section 423(b)(8) of the Code, an Eligible Employee participating in the 423 Component may be granted Purchase Rights under the Plan only if such Purchase Rights, together with any other rights granted under all Employee Stock Purchase Plans of the Company and any Related Corporations, do not permit such Eligible Employee’s rights to purchase stock of the Company or any Related Corporation to accrue at a rate which exceeds $25,000 of Fair Market Value of such stock (determined at the time such rights are granted, and which, with respect to the Plan, shall be determined as of their respective Offering Dates) for each calendar year in which such rights are outstanding at any time.

(e) Officers of the Company and any Designated Company, if they are otherwise Eligible Employees, shall be eligible to participate in Offerings under the Plan. Notwithstanding the foregoing, the Board may provide in an Offering under the 423 Component that Employees who are highly compensated Employees within the meaning of Section 423(b)(4)(D) of the Code shall not be eligible to participate.

(a) On each Offering Date, each Eligible Employee, pursuant to an Offering made under the Plan, shall be granted a Purchase Right to purchase up to that number of shares of Common Stock purchasable either with a percentage or with a maximum dollar amount, as designated by the Board, but in either case not exceeding 20% of such Employee’s earnings (as defined by the Board in each Offering) during the period that begins on the Offering Date (or such later date as the Board determines for a particular Offering) and ends on the date stated in the Offering, which date shall be no later than the end of the Offering.

(b) The Board shall establish one or more Purchase Dates during an Offering as of which Purchase Rights granted pursuant to that Offering shall be exercised and purchases of shares of Common Stock shall be carried out in accordance with such Offering.

(c) In connection with each Offering made under the Plan, the Board may specify a maximum number of shares of Common Stock that may be purchased by any Participant on any Purchase Date during such Offering. In connection with each Offering made under the Plan, the Board may specify a maximum aggregate number of shares of Common Stock that may be purchased by all Participants pursuant to such Offering. In addition, in connection with each Offering that contains more than one Purchase Date, the Board may specify a maximum

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aggregate number of shares of Common Stock that may be purchased by all Participants on any Purchase Date under the Offering. If the aggregate purchase of shares of Common Stock issuable upon exercise of Purchase Rights granted under the Offering would exceed any such maximum aggregate number, then, in the absence of any Board action otherwise, a pro rata allocation of the shares of Common Stock available shall be made in as nearly a uniform manner as shall be practicable and equitable.

(d) The purchase price of shares of Common Stock acquired pursuant to Purchase Rights shall be not less than the lesser of:

(i) an amount equal to 85% of the Fair Market Value of the shares of Common Stock on the Offering Date; or

(ii) an amount equal to 85% of the Fair Market Value of the shares of Common Stock on the applicable Purchase Date.

(a) An Eligible Employee may elect to authorize payroll deductions pursuant to an Offering under the Plan by completing and delivering to the Company, within the time specified in the Offering, an enrollment form (in such form as the Company may provide). Each such enrollment form shall authorize an amount of Contributions expressed as a percentage of the submitting Participant’s earnings (as defined in each Offering) during the Offering (not to exceed the maximum percentage specified by the Board). Each Participant’s Contributions shall be credited to a bookkeeping account for such Participant under the Plan and shall be deposited with the general funds of the Company except where applicable law requires that Contributions be deposited with a third party. To the extent provided in the Offering, a Participant may begin such Contributions after the beginning of the Offering. To the extent provided in the Offering, a Participant may thereafter reduce (including to zero) or increase his or her Contributions. To the extent required under applicable law or if specifically provided in the Offering, in addition to or instead of making Contributions by payroll deductions, a Participant may make Contributions through the payment by cash or check prior to each Purchase Date of the Offering.

(b) During an Offering, a Participant may cease making Contributions and withdraw from the Offering by delivering to the Company a notice of withdrawal in such form as the Company may provide. Such withdrawal may be elected at any time prior to the end of the Offering, except as provided otherwise in the Offering. Upon such withdrawal from the Offering by a Participant, the Company shall distribute to such Participant all of his or her accumulated Contributions (reduced to the extent, if any, such Contributions have been used to acquire shares of Common Stock for the Participant) under the Offering, and such Participant’s Purchase Right in that Offering shall thereupon terminate. A Participant’s withdrawal from an Offering shall have no effect upon such Participant’s eligibility to participate in any other Offerings under the Plan, but such Participant shall be required to deliver a new enrollment form in order to participate in subsequent Offerings.

(c) Unless otherwise required by applicable law, Purchase Rights granted pursuant to any Offering under the Plan shall terminate immediately upon a Participant ceasing to be an

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Employee for any reason or for no reason or other lack of eligibility. The Company shall distribute to such terminated or otherwise ineligible Employee all of his or her accumulated Contributions (reduced to the extent, if any, such Contributions have been used to acquire shares of Common Stock for the terminated or otherwise ineligible Employee) under the Offering.

(d) Purchase Rights shall not be transferable by a Participant except by will, the laws of descent and distribution, or by a beneficiary designation as provided in Section 10. During a Participant’s lifetime, Purchase Rights shall be exercisable only by such Participant.

(e) Unless otherwise specified in an Offering, the Company shall have no obligation to pay interest on Contributions, unless otherwise required by applicable law.

(a) On each Purchase Date during an Offering, each Participant’s accumulated Contributions shall be applied to the purchase of shares of Common Stock up to the maximum number of shares of Common Stock permitted pursuant to the terms of the Plan and the applicable Offering, at the purchase price specified in the Offering. No fractional shares shall be issued upon the exercise of Purchase Rights unless specifically provided for in the Offering.

(b) If any amount of accumulated Contributions remains in a Participant’s account after the purchase of shares of Common Stock and such remaining amount is less than the amount required to purchase one share of Common Stock on the final Purchase Date of an Offering, then such remaining amount shall be held in such Participant’s account for the purchase of shares of Common Stock under the next Offering under the Plan, unless such Participant withdraws from such next Offering, as provided in Section 7(b), or is not eligible to participate in such Offering, as provided in Section 5, in which case such amount shall be distributed to such Participant after the final Purchase Date, without interest (unless otherwise required by applicable law). If the amount of Contributions remaining in a Participant’s account after the purchase of shares of Common Stock is at least equal to the amount required to purchase one whole share of Common Stock on the final Purchase Date of the Offering, then such remaining amount shall be distributed in full to such Participant at the end of the Offering without interest (unless otherwise required by applicable law.

(c) No Purchase Rights may be exercised to any extent unless the shares of Common Stock to be issued upon such exercise under the Plan are covered by an effective registration statement pursuant to the Securities Act and the Plan is in material compliance with all applicable federal, state, foreign and other securities and other laws applicable to the Plan. If on a Purchase Date during any Offering hereunder the shares of Common Stock are not so registered or the Plan is not in such compliance, no Purchase Rights or any Offering shall be exercised on such Purchase Date, and the Purchase Date shall be delayed until the shares of Common Stock are subject to such an effective registration statement and the Plan is in such compliance, except that the Purchase Date shall not be delayed more than 12 months and the Purchase Date shall in no event be more than 27 months from the Offering Date. If, on the Purchase Date under any Offering hereunder, as delayed to the maximum extent permissible, the shares of Common Stock are not registered and the Plan is not in such compliance, no Purchase Rights shall be exercised and all Contributions accumulated during the Offering (reduced to the extent, if any, such Contributions have been used to acquire shares of Common Stock) shall be distributed to the Participants without interest.

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The Company shall seek to obtain from each federal, state, foreign or other regulatory commission or agency having jurisdiction over the Plan such authority as may be required to issue and sell shares of Common Stock upon exercise of the Purchase Rights. If, after commercially reasonable efforts, the Company is unable to obtain from any such regulatory commission or agency the authority that counsel for the Company deems necessary for the lawful issuance and sale of Common Stock under the Plan, and at a commercially reasonable cost, the Company shall be relieved from any liability for failure to issue and sell Common Stock upon exercise of such Purchase Rights unless and until such authority is obtained.

(a) A Participant may file a written designation of a beneficiary who is to receive any shares of Common Stock and/or cash, if any, from the Participant’s account under the Plan in the event of such Participant’s death subsequent to the end of an Offering but prior to delivery to the Participant of such shares of Common Stock or cash. In addition, a Participant may file a written designation of a beneficiary who is to receive any cash from the Participant’s account under the Plan in the event of such Participant’s death during an Offering. Any such designation shall be on a form provided by or otherwise acceptable to the Company.

(b) The Participant may change such designation of beneficiary at any time by written notice to the Company. In the event of the death of a Participant and in the absence of a beneficiary validly designated under the Plan who is living at the time of such Participant’s death, the Company shall deliver such shares of Common Stock and/or cash to the executor or administrator of the estate of the Participant, or if no such executor or administrator has been appointed (to the knowledge of the Company), the Company, in its sole discretion, may deliver such shares of Common Stock and/or cash to the spouse or to any one or more dependents or relatives of the Participant, or if no spouse, dependent or relative is known to the Company, then to such other person as the Company may designate.

(a) In the event of a Capitalization Adjustment, the Board shall appropriately and proportionately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), (ii) the class(es) and number of securities subject to, and the purchase price applicable to outstanding Offerings and Purchase Rights, and (iii) the class(es) and number of securities that are the subject of purchase limits under each ongoing Offering. The Board shall make such adjustments, and its determination shall be final, binding and conclusive.

(b) In the event of a Corporate Transaction, then: (i) any surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company) may assume or continue Purchase Rights outstanding under the Plan or may substitute similar rights (including a right to acquire the same consideration paid to the stockholders in the Corporate Transaction) for those outstanding under the Plan, or (ii) if any surviving or acquiring

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corporation (or its parent company) does not assume or continue such Purchase Rights or does not substitute similar rights for Purchase Rights outstanding under the Plan, then the Participants’ accumulated Contributions shall be used to purchase shares of Common Stock within ten business days prior to the Corporate Transaction under any ongoing Offerings, and the Participants’ Purchase Rights under the ongoing Offerings shall terminate immediately after such purchase.

(i) The Board may amend the Plan at any time in any respect the Board deems necessary or advisable. However, except as provided in Section 11(a) relating to Capitalization Adjustments, stockholder approval shall be required for any amendment of the Plan for which stockholder approval is required by applicable law or listing requirements, including any amendment that either (i) materially increases the number of shares of Common Stock available for issuance under the Plan, (ii) materially expands the class of individuals eligible to become Participants and receive Purchase Rights under the Plan, (iii) materially increases the benefits accruing to Participants under the Plan or materially reduces the price at which shares of Common Stock may be purchased under the Plan, (iv) materially extends the term of the Plan, or (v) expands the types of awards available for issuance under the Plan, but in each of (i) through (v) above only to the extent stockholder approval is required by applicable law or listing requirements.

(b) The Board may suspend or terminate the Plan at any time. No Purchase Rights may be granted under the Plan while the Plan is suspended or after it is terminated.

(c) Any benefits, privileges, entitlements and obligations under any outstanding Purchase Rights granted before an amendment, suspension or termination of the Plan shall not be impaired by any such amendment, suspension or termination except (i) with the consent of the person to whom such Purchase Rights were granted, (ii) as necessary to comply with any laws, listing requirements, or governmental regulations (including, without limitation, the provisions of Section 423 of the Code and the regulations and other interpretive guidance issued thereunder relating to Employee Stock Purchase Plans) including without limitation any such regulations or other guidance that may be issued or amended after the Effective Date, or (iii) as necessary to obtain or maintain favorable tax, listing, or regulatory treatment.

(a) Purchase Rights granted under the 423 Component are exempt from the application of Section 409A of the Code. Purchase Rights granted under the Non-423 Component to U.S. taxpayers are intended to be exempt from the application of Section 409A of the Code under the short-term deferral exception and any ambiguities shall be construed and interpreted in accordance with such intent. Subject to Section 13(b) hereof, Purchase Rights granted to U.S. taxpayers under the Non-423 Component shall be subject to such terms and conditions that will permit such Purchase Rights to satisfy the requirements of the short-term deferral exception available under Section 409A of the Code, including the requirement that the shares subject to a Purchase Right be delivered within the short-term deferral period. Subject to Section 13(b) hereof, in the case of a Participant who would otherwise be subject to Section

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409A of the Code, to the extent the Board determines that a Purchase Right or the exercise, payment, settlement or deferral thereof is subject to Section 409A of the Code, the Purchase Right shall be granted, exercised, paid, settled or deferred in a manner that will comply with Section 409A of the Code, including U.S. Department of Treasury regulations and other interpretive guidance issued thereunder, including without limitation any such regulations or other guidance that may be issued after the adoption of the Plan. Notwithstanding the foregoing, the Company shall have no liability to a Participant or any other party if the Purchase Right that is intended to be exempt from or compliant with Section 409A of the Code is not so exempt or compliant or for any action taken by the Board with respect thereto.

(b) Although the Company may endeavor to (i) qualify a Purchase Right for favorable tax treatment under the laws of the United States or jurisdictions outside of the United States or (ii) avoid adverse tax treatment (e.g., under Section 409A of the Code), the Company makes no representation to that effect and expressly disavows any covenant to maintain favorable or avoid unfavorable tax treatment, notwithstanding anything to the contrary in this Plan, including Section 13(a) hereof. The Company shall be unconstrained in its corporate activities without regard to the potential negative tax impact on Participants under the Plan.

The Plan shall become effective on the date the Plan is adopted by the Board (the “Effective Date”) but no Purchase Rights shall be exercised unless and until the Plan has been approved by the stockholders of the Company, which approval shall be within 12 months before or after the date the Plan is adopted by the Board.

(a) Proceeds from the sale of shares of Common Stock pursuant to Purchase Rights shall constitute general funds of the Company.

(b) A Participant shall not be deemed to be the holder of, or to have any of the rights of a holder with respect to, shares of Common Stock subject to Purchase Rights unless and until the Participant’s shares of Common Stock acquired upon exercise of Purchase Rights are recorded in the books of the Company (or its transfer agent).

(c) The Plan and Offering do not constitute an employment contract. Nothing in the Plan or in the Offering shall in any way alter the at will nature of a Participant’s employment, if applicable, or be deemed to create in any way whatsoever any obligation on the part of any Participant to continue in the employ of the Company, a Related Corporation or an Affiliate, or on the part of the Company, a Related Corporation or an Affiliate to continue the employment of a Participant.

(d) The provisions of the Plan shall be governed by the laws of the State of Delaware without resort to that state’s conflicts of laws rules.

(e) If any particular provision of the Plan is found to be invalid or otherwise unenforceable, such provision shall not affect the other provisions of the Plan, but the Plan shall be construed in all respects as if such invalid provision were omitted.

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As used in the Plan, the following definitions shall apply to the capitalized terms indicated below:

(a) “423 Component” means the part of the Plan, which excludes the Non-423 Component, pursuant to which Purchase Rights that satisfy the requirements for Employee Stock Purchase Plans may be granted to Eligible Employees.

(b) “Affiliate” means (i) any entity that, directly or indirectly, is controlled by, controls or is under common control with, the Company and (ii) any entity in which the Company has a significant equity interest, in either case as determined by the Board, whether now or hereafter existing.

(c) “Board” means the Board of Directors of the Company.

(d) “Capitalization Adjustment” means any change that is made in, or other events that occur with respect to, the Common Stock subject to the Plan or subject to any Purchase Right after the Effective Date 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 similar transaction). Notwithstanding the foregoing, the conversion of any convertible securities of the Company shall not be treated as a Capitalization Adjustment.

(e) “Code” means the U.S. Internal Revenue Code of 1986, as amended, including any applicable regulations and guidance thereunder.

(f) “Committee” means a committee of one or more members of the Board to whom authority has been delegated by the Board in accordance with Section 2(c).

(g) “Common Stock” means the common stock of the Company.

(h) “Company” means NetScout Systems, Inc., a Delaware corporation.

(i) “Contributions” means the payroll deductions and other additional payments specifically provided for in the Offering, that a Participant contributes to fund the exercise of a Purchase Right. A Participant may make additional payments into his or her account, if specifically provided for in the Offering, and then only if the Participant has not already had the maximum permitted amount withheld during the Offering through payroll deductions.

(j) “Corporate Transaction” means the consummation, in a single transaction or in a series of related transactions, of any one or more of the following events:

(i) a sale or other disposition of all or substantially all, as determined by the Board in its sole discretion, of the consolidated assets of the Company and its Subsidiaries;

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(ii) a sale or other disposition of at least 90% of the outstanding securities of the Company;

(iii) a merger, consolidation or similar transaction following which the Company is not the surviving corporation; or

(iv) a merger, consolidation or similar transaction following which the Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the merger, consolidation or similar transaction are converted or exchanged by virtue of the merger, consolidation or similar transaction into other property, whether in the form of securities, cash or otherwise.

(k) “Designated Affiliate” means any Affiliate selected by the Board as eligible to participate in the Non-423 Component.

(l) “Designated Company” means a Designated Affiliate or Designated Related Corporation.

(m) “Designated Related Corporation” means any Related Corporation selected by the Board as eligible to participate in the 423 Component. A Related Corporation incorporated in the United States is deemed selected by the Board as eligible to participate in the 423 Component, unless expressly otherwise provided by the Board.

(n) “Director” means a member of the Board.

(o) “Eligible Employee” means an Employee who meets the requirements set forth in the Offering for eligibility to participate in the Offering, provided that such Employee also meets the requirements for eligibility to participate set forth in the Plan.

(p) “Employee” means any person, including Officers and Directors, who is treated as an employee in the records of the Company, a Related Corporation or an Affiliate. However, service solely as a Director, or payment of a fee for such services, shall not cause a Director to be considered an “Employee” for purposes of the Plan. Consultants and independent contractors are not “Employees” for purposes of the Plan.

(q) “Employee Stock Purchase Plan” means a plan that grants Purchase Rights intended to be options issued under an “employee stock purchase plan,” as that term is defined in Section 423(b) of the Code.

(r) “Exchange Act” means the U.S. Securities Exchange Act of 1934, as amended.

(s) “Fair Market Value” means, as of any date, the value of the Common Stock determined as follows:

(i) If the Common Stock is listed on any established stock exchange or traded on any established market, the Fair Market Value of a share of Common Stock shall be the closing sales price for such stock as quoted on such exchange or market (or the exchange or market with the greatest volume of trading in the Common Stock) on the date of determination,

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as reported in such source as the Board deems reliable. Unless otherwise provided by the Board, if there is no closing sales price for the Common Stock on the date of determination, then the Fair Market Value shall be the closing selling price (or closing bid if no sales were reported) on the last preceding date for which such quotation exists.

(ii) In the absence of such markets for the Common Stock, the Fair Market Value shall be determined by the Board in good faith and in a manner that complies with Sections 409A of the Code.

(t) “Non-423 Component” means an employee stock purchase plan which is not intended to meet the requirements set forth in Code Section 423 and the regulations thereunder.

(u) “Offering” means the grant of Purchase Rights to purchase shares of Common Stock under the Plan to Eligible Employees.

(v) “Offering Date” means a date selected by the Board for an Offering to commence.

(w) “Officer” means a person who is an officer of the Company, an Affiliate or a Related Corporation within the meaning of Section 16 of the Exchange Act.

(x) “Participant” means an Eligible Employee who holds an outstanding Purchase Right granted pursuant to the Plan.

(y) “Plan” means this NetScout Systems, Inc. 2011 Employee Stock Purchase Plan, including both the 423 and Non-423 Components, as amended from time to time.

(z) “Purchase Date” means one or more dates during an Offering established by the Board on which Purchase Rights shall be exercised and as of which purchases of shares of Common Stock shall be carried out in accordance with such Offering.

(aa) “Purchase Period” means a period of time specified within an Offering beginning on the Offering Date or on the next day following a Purchase Date within an Offering and ending on a Purchase Date. An Offering may consist of one or more Purchase Periods.

(bb) “Purchase Right” means an option to purchase shares of Common Stock granted pursuant to the Plan.

(cc) “Related Corporation” means any “parent corporation” or “subsidiary corporation” of the Company whether now or subsequently established, as those terms are defined in Sections 424(e) and (f), respectively, of the Code.

(dd) “Securities Act” means the U.S. Securities Act of 1933, as amended.

(ee) “Trading Day” means any day on which the exchange(s) or market(s) on which shares of Common Stock are listed, including the Nasdaq Global Select Market, the Nasdaq Global Market, or the Nasdaq Capital Market, is open for trading.

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