Exhibit 10.21

EMPLOYMENT AGREEMENT

THIS EMPLOYMENT AGREEMENT (the "Agreement") is made and entered into as of this 18th day of October, 2002 (the "Effective Date"), by and between
VitalStream, Inc., a Delaware corporation (the "Company"), and Kevin D. Herzog ("Employee"). In consideration of the mutual covenants set forth below, the Company and Employee hereby agree as
follows:

1.At Will Employment.The Company hereby employs Employee, and Employee hereby accepts employment by the
Company. The parties acknowledge and agree that the Employee's employment relationship is "at-will", meaning that either party may terminate the employment relationship for any reason at
any time, with or without cause or prior notice. Any termination of Employee by the Company shall be by action of the Board of Directors of the Company.

2.Services.Employee shall serve as Chief Financial Officer of the Company and perform such services for the
Company as are customary for such position and as may be assigned to him from time to time by the Board of Directors of the Company.

3.Restrictive Covenant During Term.During his employment by the Company, Employee shall devote his full time
and services exclusively to the Company and will not, without the prior written consent of the Board of Directors of the Company, own, either directly or indirectly, any interest in any
privately-held business or commercial enterprise which is competitive with the business conducted by the Company. Furthermore, Employee shall not, without the prior written consent of the
Board of Directors of the Company, serve as a partner, officer, director, advisor or employee of, or act in any other similar capacity for, any business or commercial enterprise which is competitive
with the business conducted by the Company. However, nothing contained in this Paragraph 3 shall be construed to prohibit Employee from purchasing the capital stock or other securities of any
corporation or other business entity whose stock or securities are traded on any national or regional securities exchange or in the national over-the-counter market.

4.Compensation.



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5.Employee Benefits.



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6.Confidential Information.



7.Non-Solicitation.Employee shall not, for a period of 12 months following the termination
of his employment with the Company, for any reason whatsoever, directly or indirectly, for himself or for, on behalf of or in conjunction with any other person or entity, (a) solicit or induce
any employee, agent, independent contractor or consultant of or to the Company to terminate his, her or its employment or other relationship with the Company for the purpose of associating with any
competitor of the Company or otherwise encourage any such person to leave or sever his, her or its employment or other relationship with the Company; or (b) solicit, induce, or attempt to
solicit or induce any customers, clients, vendors, suppliers or consultants of or to the Company to terminate or change his, her or its relationship with the Company for the purpose of associating
with any competitor of the Company, or otherwise encourage such customers, clients, vendors, suppliers or consultants of the Company to terminate or change his, her or its relationship with the
Company for any reason.

8.Damages and Injunction.Because of the difficulty of measuring economic losses to the Company as a result of
a breach by Employee of the provisions of Sections 6 and 7 hereof, and because of the immediate and irreparable damage that could be caused for which it would have no other adequate remedy,
Employee agrees that the provisions of Sections 6 and 7 hereof may be enforced by the
Company in the event of breach or threatened breach by Employee, by injunctions and restraining orders without having to post a bond or other security. Nothing herein shall be construed as prohibiting
the Company from pursuing any other available remedy for such breach or threatened breach, including the recovery of damages.

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9.Agency and Authority.Employee agrees that his employment by the Company shall constitute him an agent for
the Company only for such purposes as are customary for his position. Employee agrees that he will not act or purport to act in any way for the Company, except as to matters directly related to his
employment.

10.Severability.Nothing contained in this Agreement shall be construed as requiring the commission of any act
contrary to law, and wherever there is any conflict between any provision of this Agreement and any present or future statute, law, ordinance or regulation contrary to which the parties have no legal
right to contract, the latter shall prevail, but in such event, the provision of this Agreement thus affected shall be curtailed and limited only to the extent necessary to bring it within the
requirements of the law. In the event that any part, article, paragraph or clause of this Agreement shall be held to be indefinite or invalid, the entire Agreement shall not fail on account thereof,
and the balance of the Agreement shall continue in full force and effect.

11.Notices.Any notice required to be given under this Agreement shall be in writing and shall be deemed
effective upon personal delivery or three (3) days after deposit in the U.S. mail, postage prepaid and properly addressed to the party entitled to such notice, at the address indicated beside
such party's signature line on this Agreement or at such other address as such party may designate by ten (10) days advance written notice under this paragraph to all other parties to this
Agreement.

12.Amendment.Any waiver, alteration or modification of any of the provisions of this Agreement or cancellation
or replacement of this Agreement shall not be valid unless made in writing and signed by the parties hereto.

13.Governing Law.This Agreement shall be construed and governed in accordance with the laws of the State of
California applicable to contracts executed and to be wholly performed within the State of California.

14.Waiver.Waiver by either party of the breach of any provision of this Agreement shall not operate or be
construed as a waiver of any subsequent breach.

15.Arbitration.In the event of any dispute or any claim arising out of this agreement, the termination of
Employee's employment, or the employment relationship between the Employee and the Company (including, but not limited to, any claims of wrongful termination or claims for discrimination based on
race, age, sex, disability, creed, color, religion, sexual orientation, marital status, or any other protected category, under California Fair Employment and Housing Act, Title VII of the Civil
Rights Act, Age Discrimination in Employment Act, or Americans with Disabilities Act), Employee and the Company agree that all such disputes shall be fully and finally resolved by binding arbitration
conducted under the rules of the American Arbitration Association Employment Dispute Resolution Rules at Los Angeles, California. The parties shall be permitted reasonable discovery and the
arbitrator shall render a written award setting forth his findings of fact and conclusions of law. Each party shall bear his or its own expenses incurred in connection with the arbitration, including
attorneys' fees and costs. The Company shall pay the arbitrator's fees. The parties waive the right to have disputes tried by a court or jury. This arbitration provision shall not apply to claims for
unemployment insurance benefits filed with the Employment Development Department or to claims for normal workers compensation benefits filed with the Workers Compensation Appeals Board.

16.Entire Agreement.This Agreement contains all the terms and conditions agreed upon by the parties hereto and
sets forth the entirety of the consideration to which Employee shall be entitled hereunder. No other agreements, oral or otherwise, shall be deemed to exist or to bind any of the parties hereto in any
manner related to this Agreement. No officer or employee of the Company has any authorization to make any representation or promise in any manner related to this Agreement not contained in this
Agreement, and Employee agrees that he has not executed this Agreement in reliance

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upon any such representation or promise. This Agreement cannot be modified or changed except by written instrument, signed by both parties hereto.

17.Paragraph Headings.The headings of this Agreement are for purposes of reference only and shall not limit or
otherwise affect the meaning hereof.

18.Counterparts.This Agreement may be executed in a number of counterparts, each of which shall be construed
as an original for all purposes.

IN
WITNESS WHEREOF, the parties hereto have executed this Agreement as of the day and year first above written.

|         |  | VITALSTREAM, INC.                       
|-------- |  | ----------------------------------------
|         |  | By:                                     
|         |  | Its:                                    
|         |  | Date:                                   
|Address: |  |                                         
|         |  | EMPLOYEE                                
|         |  | /s/KEVIN D. HERZOGDate: October 21, 2002

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