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                                 PROMISSORY NOTE


$500,000                                                    Salt Lake City, Utah
                                                               February 14, 2002

         For the value received, VitalStream, Inc., a Delaware corporation, (the
"MAKER"), promises to pay to Sensar Corporation, a Nevada corporation (the
"LENDER") or order, at 136 East South Temple, Suite 2325, Salt Lake City, Utah
84111, or such other place as the holder hereof may designate, the principal sum
of $500,000, or such lesser amount as shall have actually been advanced by
Lender to Maker, with interest from the date hereof on the unpaid principal.

         1. THE NOTE. This Promissory Note (this "NOTE") is being issued by
Maker pursuant to the Loan and Security Agreement dated as of even date herewith
(as amended from time to time, the "LOAN AGREEMENT") by and between Maker and
Lender. (The principal balance of this Note that is outstanding and unpaid from
time to time is referred to as the "PRINCIPAL AMOUNT"; and the PRINCIPAL AMOUNT,
together with all accrued interest and all other amounts owing under this Note
is referred to as the "OUTSTANDING INDEBTEDNESS.")

         2. INTEREST RATE. If VitalStream Operating Corporation, a Delaware
corporation ("Merger Sub"), and the Maker file articles of merger with the state
of Delaware effecting the merger of Merger Sub with and into Maker (the
"MERGER") on or before June 30, 2002 (the "MERGER DEADLINE"), then interest
shall accrue under this Note at the rate of 6% per annum. If the Merger does not
occur on or before the Merger Deadline, or if the Agreement and Plan of Merger
dated February 13, 2002, among Maker, Lender and Merger Sub (the "MERGER
AGREEMENT") is terminated pursuant to Section 7.1 thereof, interest shall
accrued under this Note at the rate of 12% per annum. (The interest rate
calculated pursuant to this paragraph is referred to as the "INTEREST RATE.")
Interest shall be calculated using the actual number of days elapsed divided by
360.

         3. REPAYMENT. The Principal Amount, accrued and unpaid interest and all
other Outstanding Indebtedness shall be due and payable in a single installment
due on July 31, 2002. All amounts of Outstanding Indebtedness shall be paid in
immediately available funds. All payments shall be credited first to accrued but
unpaid interest due under this Note, second, to the reduction of the outstanding
Principal Amount, and third, to any other Outstanding Indebtedness. Maker may
prepay this Note in whole or in part at any time without penalty.

         4. LATE FEE. If Maker fails to make any payment due under this Note on
or before the date due, then Maker shall pay a late fee equal to 10% of the
payment amount due and this late fee shall not be a penalty.

         5. EVENTS OF DEFAULT. As used herein, the term "EVENT OF DEFAULT" means
any occurrence constituting an Event of Default as defined in the Loan
Agreement. If an Event of Default occurs, then Lender may at any time (unless
all defaults shall theretofore have been


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remedied) at Lender's option, without notice to Maker or any other person,
declare the entire principal and interest of this Note then remaining unpaid
to be due and payable immediately. Any forbearance, failure or delay by
Lender in exercising any right or remedy under this Note or otherwise
available to Lender shall not be deemed to be a waiver of such right or
remedy, nor shall any single or partial exercise of any right or remedy
preclude the further exercise of such right or remedy.

         6. COSTS. In the event that (a) any payment under this Note is not made
at the time and in the manner required hereunder, (b) the holder hereof incurs
any costs of collection or other costs reasonably necessary for the protection
of the interest of Lender with respect to this Note, or (c) the holder hereof
exercises its right to accelerate the maturity of the obligations hereunder,
Maker agrees to pay any and all costs and expenses (regardless of the particular
nature thereof and whether incurred before or after the initiation of suit or
before or after judgment) which may be incurred by the holder hereof in
connection with the enforcement of any of its rights under this Note, including
court costs and attorneys' fees.

         7. WAIVERS. Maker hereby waives presentment by Lender for payment,
demand, notice of dishonor and nonpayment of this Note, and Maker consents to
any and all extensions of time, renewals, waivers or modifications that may be
granted by Lender with respect to the payment or other provisions of this Note
and to the release of any security or any part thereof, with or without
substitution.

         8.   SECURITY AGREEMENT. This Note is secured by the Loan Agreement.

         9. GOVERNING LAW; VENUE. This Note is delivered in the state of Nevada
and shall be governed by and construed in accordance with the laws of the state
of Nevada without reference to its choice of law rules. Each of the parties
submits to the jurisdiction of any state or federal court sitting in the State
of Nevada, County of Clark in any action or proceeding arising out of or
relating to this Note and agrees that all claims in respect of the action or
proceeding may be heard and determined in any such court. Each of the parties
waives any defense of inconvenient forum to the maintenance of any action or
proceeding so brought and waives any bond, surety, or other security that might
be required of any other party with respect thereto.

         10. SEVERABILITY. If for any reason one or more of the provisions of
this Note or their application to any person or circumstances shall be held to
be invalid, illegal or unenforceable in any respect or to any extent, such
provisions shall nevertheless remain valid, legal and enforceable in all such
other respects and to such extent as may be permissible. In addition, any such
invalidity, illegality or unenforceability shall not affect any other provisions
of this Note, and this Note shall be construed as if such invalid, illegal or
unenforceable provision had never been contained therein.

         11. SUCCESSORS AND ASSIGNS; TRANSFERABILITY. This Note inures to the
benefit of Lender and binds Maker, and its respective successors and assigns.
This Note shall not be transferable or assignable, by operation of law or
otherwise, by Maker without the prior express written

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consent of Lender (Lender hereby consents to the transfer of this Note to
Merger Sub in connection with the Merger). Any transfer in violation of this
provision shall be void ab initio. The Lender may assign this Note at any
time without the consent of the Maker. Following the effective date of any
assignment by Lender, Lender shall provide Maker immediate notice of such
assignment, which notice shall identify the assignee and provide the address
and facsimile number of such assignee. Unless and until Maker receives a
notice of an assignment, Maker shall be permitted to recognize the Lender as
holders of this Note and shall not be liable for any payment made to Lender
instead of the assignee of this Note. Following receipt of notice of an
assignment of this Note, Maker shall recognize the assignee as Payee for all
purposes under this Note.

         12. CAPTIONS. The captions or headings of the paragraphs in this Note
are for convenience only and shall not control or affect the meaning or
construction of any of the terms or provisions of this Note.

         13. NOTICE AND ACKNOWLEDGMENT OF REPRESENTATIVE. All notices and other
communications required or permitted hereunder shall be in writing and shall
delivered in accordance with the notice provisions of the Merger Agreement.

         IN WITNESS WHEREOF, the undersigned have executed this Note on the date
first written above.

                                     MAKER:

                                                  VITALSTREAM, INC.


                                                  By: /s/ Paul Summers
                                                      --------------------------
                                                       Name: Paul Summers
                                                       Title: President



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