Exhibit 4.3

THIS GLOBAL NOTE IS HELD BY THE DEPOSITARY (AS DEFINED IN THE INDENTURE GOVERNING THIS NOTE) OR ITS NOMINEE IN CUSTODY FOR THE BENEFIT OF THE BENEFICIAL OWNERS HEREOF. UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR NOTES IN DEFINITIVE FORM, THIS NOTE MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR DEPOSITARY. UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (55 WATER STREET, NEW YORK, NEW YORK) (“DTC”), TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS MAY BE REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR SUCH OTHER ENTITY AS MAY BE REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN

2.500% SENIOR NOTES DUE 2015

COMPUTER SCIENCES CORPORATION

Computer Sciences Corporation, a Nevada corporation (the “Company”), promises to pay to Cede & Co. or registered assigns, the principal sum of Three Hundred Fifty Million Dollars ($350,000,000) on September 15, 2015.

Interest Payment Dates: March 15 and September 15

Record Dates: March 1 and September 1

Each holder of this Note (as defined below), by accepting the same, agrees to and shall be bound by the provisions hereof and of the Indenture described herein, and authorizes and directs the Trustee described herein on such holder’s behalf to be bound by such provisions. Each holder of this Note hereby waives all notice of the acceptance of the provisions contained herein and in the Indenture and waives reliance by such holder upon said provisions.

This Note shall not be entitled to any benefit under the Indenture, or be valid or become obligatory for any purpose, until the Certificate of Authentication hereon shall have been manually signed by or on behalf of the Trustee. The provisions of this Note are continued on the reverse side hereof, and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, the Company has caused this Note to be signed in accordance with Section 2.4 of the Base Indenture.

Date: September 18, 2012

2.500% Senior Note due 2015

CERTIFICATE OF AUTHENTICATION

This is one of the 2.500% Senior Notes due 2015 issued by Computer Sciences Corporation of the series designated therein referred to in the within-mentioned Indenture.

Date: September 18, 2012

2.500% Senior Note due 2015

Computer Sciences Corporation

2.500% Senior Notes due 2015

This note is one of a duly authorized series of debt securities of Computer Sciences Corporation, a Nevada corporation (the “Company”), issued or to be issued in one or more series under and pursuant to an Indenture for the Company’s debentures, notes or other debt instruments evidencing its Indebtedness, dated as of September 18, 2012 (the “Base Indenture”), duly executed and delivered by and among the Company and The Bank of New York Mellon Trust Company, N.A. (the “Trustee”), as supplemented by the First Supplemental Indenture, dated as of September 18, 2012 (the “First Supplemental Indenture”), by and between the Company and the Trustee. The Base Indenture as supplemented and amended by the First Supplemental Indenture is referred to herein as the “Indenture.” By the terms of the Base Indenture, the debt securities issuable thereunder are issuable in series that may vary as to amount, date of maturity, rate of interest and in other respects as provided in the Base Indenture. This note is one of the series designated on the face hereof (individually, a “Note,” and collectively, the “Notes”), and reference is hereby made to the Indenture for a description of the rights, limitations of rights, obligations, duties and immunities of the Trustee, the Company and the Holders of the Notes (the “Holders”). Capitalized terms used herein and not otherwise defined shall have the meanings given them in the Base Indenture or the First Supplemental Indenture, as applicable.

1. Interest. The rate at which the Notes shall bear interest shall be 2.500% per year. The date from which interest shall accrue on the Notes shall be September 18, 2012, or the most recent Interest Payment Date to which interest has been paid or provided for. The Interest Payment Dates for the Notes shall be March 15 and September 15 of each year, beginning March 15, 2013. Interest shall be payable on each Interest Payment Date to the holders of record at the close of business on the March 1 and September 1 prior to each Interest Payment Date. The basis upon which interest shall be calculated shall be that of a 360-day year consisting of twelve 30-day months.

2. Method of Payment. The Company will pay interest on the Notes (except defaulted interest), if any, to the persons in whose name such Notes are registered at the close of business on the regular record date referred to on the facing page of this Note for such interest installment. In the event that the Notes or a portion thereof are called for redemption and the Redemption Date is subsequent to a regular record date with respect to any Interest Payment Date and prior to such Interest Payment Date, interest on such Notes will be paid upon presentation and surrender of such Notes as provided in the Indenture. The principal of and the interest on the Notes shall be payable in Dollars, at the office or agency of the Company maintained for that purpose in accordance with the Indenture.

3. Paying Agent and Registrar. Initially, the Trustee will act as Paying Agent and Registrar. The Company may change or appoint any Paying Agent or Registrar without notice to any Holder.

4. Indenture. The terms of the Notes include those stated in the Indenture and those made part of the Indenture by reference to the Trust Indenture Act of 1939 (“TIA”) as in effect on the date the Indenture is qualified. The Notes are subject to all such terms, and Holders are referred to the Indenture and TIA for a statement of such terms. The Notes are senior unsecured obligations of the Company and constitute the series designated on the face hereof as the “2.500% Senior Notes due 2015”, initially limited to $350,000,000 in aggregate principal amount. The Company will furnish to any Holders upon written request and without charge a copy of the Base Indenture and the First Supplemental Indenture. Requests may be made to: Computer Sciences Corporation, 3170 Fairview Park Drive, Falls Church, VA 22042, Attention: General Counsel.

5. Redemption. The Notes shall be redeemable as a whole or in part, at the Company’s option, at any time or from time to time, as provided in Section 1.4 of the First Supplemental Indenture.

The Notes will not have the benefit of any sinking fund.

6. Change of Control Triggering Event. If a Change of Control Triggering Event occurs with respect to a particular series of Notes, unless the Company has exercised its option to redeem such Notes as described in Section 1.4 of the First Supplemental Indenture, the Company will make an offer to each Holder of such Notes to repurchase all or any part (equal to $2,000 or an integral multiple of $1,000 in excess thereof) of that Holder’s Notes

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at a repurchase price, payable in cash, equal to 101% of the aggregate principal amount of Notes repurchased, plus accrued and unpaid interest, on the Notes repurchased to the date of repurchase. Within 30 days following any Change of Control Triggering Event or, at the Company’s option, prior to any Change of Control, but after public announcement of the transaction that constitutes or may constitute the Change of Control, a notice will be sent to Holders of the Notes, with a copy to the Trustee, describing the transaction that constitutes or may constitute the Change of Control Triggering Event and offering to repurchase such Notes on the date specified in the notice, which date will be no earlier than 30 days and no later than 90 days from the date such notice is mailed, in accordance with Section 1.5.4 of the First Supplemental Indenture.

7. Denominations, Transfer, Exchange. The Notes are in registered form without coupons in minimum denominations of $2,000 or any integral multiple of $1,000 in excess thereof. The transfer of Notes may be registered and Notes may be exchanged as provided in Section 1.3 of the First Supplemental Indenture and Sections 2.8 and 2.16 of the Base Indenture. The Notes may be presented for exchange or for registration of transfer at the office of the Company or its agency designated by the Company for such purpose.

8. Persons Deemed Owners. The person in whose name this Note is registered may be treated as its owner for all purposes.

9. Repayment to the Company. The Trustee and the Paying Agent shall pay to the Company upon request any money held by them for the payment of principal and interest that remains unclaimed for two years. After that, Holders entitled to the money must look to the Company for payment as general creditors unless an applicable abandoned property law designates another person.

10. Amendments, Supplements and Waivers. Subject to certain exceptions, the Company and the Trustee may amend or supplement the Indenture and the Notes with the written consent (including consents obtained in connection with a tender offer or exchange offer for Notes) of the Holders of a majority in principal amount of the then outstanding Notes, and compliance with any provision of the Indenture and the Notes may be waived with the written consent (including consents obtained in connection with a tender offer or exchange offer for Notes) of the Holders of a majority in principal amount of the then outstanding Notes. The Company and the Trustee may amend or supplement the Indenture and the Notes without notice to or consent of any Holder as provided in the Indenture, including, without limitation, to cure any ambiguity, defect or inconsistency or make any change that would not adversely affect the legal rights under the Indenture of any Holder in any material respect.

11. Defaults and Remedies. If an Event of Default with respect to the Notes occurs and is continuing (other than an Event of Default in Sections 1.6.1(e) or 1.6.1(f) of the First Supplemental Indenture), then in every such case the Trustee or the Holders of not less than 25% in principal amount of the outstanding Notes may declare the principal amount of and accrued and unpaid interest, if any, on all the Notes to be due and payable immediately, by a notice in writing to the Company (and to the Trustee if given by the Holders), and upon such declaration such principal amount and accrued and unpaid interest, if any, shall become immediately due and payable. If an Event of Default specified in Sections 1.6.1(e) or 1.6.1(f) of the First Supplemental Indenture shall occur, the principal of and accrued and unpaid interest, if any, on all outstanding Notes shall ipso facto become and be immediately due and payable without any declaration or other act on the part of the Trustee or any Holder of outstanding Notes. Subject to the terms of the Indenture, if an Event of Default under the Indenture shall occur and be continuing, the Trustee will be under no obligation to exercise any of the rights or powers vested in it by the Indenture at the request or direction of any of the Holders unless such Holders shall have offered the Trustee security or indemnity satisfactory to it. Upon satisfaction of certain conditions set forth in the Indenture, the Holders of a majority in principal amount of the outstanding Notes shall have the right to direct the time, method and place of conducting any proceeding for any remedy available to the Trustee, or exercising any trust or power conferred on the Trustee, with respect to the Notes.

12. Trustee May Hold Securities. The Trustee, subject to certain limitations imposed by the TIA, in its individual or any other capacity, may become the owner or pledgee of Notes with the same rights it would have if it were not Trustee, Paying Agent or Registrar.

13. No Recourse Against Others. A director, officer, employee or stockholder (past or present), as such, of the Company shall not have any liability for any obligations of the Company under the Notes or the

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Indenture or for any claim based on, in respect of or by reason of such obligations or their creation. Each Holder by accepting a Note waives and releases all such liability. The waiver and release are part of the consideration for the issue of the Notes.

14. Discharge of Indenture. The Indenture contains certain provisions pertaining to discharge and defeasance, which provisions shall for all purposes have the same effect as if set forth herein.

15. Authentication. This Note shall not be valid until the Trustee manually signs the certificate of authentication attached to the other side of this Note.

16. Abbreviations. Customary abbreviations may be used in the name of a Holder or an assignee, such as: TEN COM (= tenants in common), TEN ENT (= tenants by the entireties), JT TEN (= joint tenants with right of survivorship and not as tenants in common), CUST (= Custodian), and U/G/M/A (= Uniform Gifts to Minors Act).

17. Governing Law. THE INDENTURE AND THIS NOTE, INCLUDING ANY CLAIM OR CONTROVERSY ARISING OUT OF OR RELATING TO THE INDENTURE OR THIS NOTE, SHALL BE GOVERNED BY THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO CONFLICT OF LAW PRINCIPLES THAT WOULD RESULT IN THE APPLICATION OF ANY LAW OTHER THAN THE LAW OF THE STATE OF NEW YORK.

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ASSIGNMENT FORM

To assign this Note, fill in the form below: (I) or (we) assign and transfer this Note to:

(Insert assignee’s soc. sec. or tax I.D. no.)

(Print or type assignee’s name, address and zip code)

Date:                     

OPTION OF HOLDER TO ELECT PURCHASE

If you want to elect to have this Note purchased by the Company pursuant to Section 1.5.4 of the First Supplemental Indenture, check the box:

If you want to elect to have only part of this Note purchased by the Company pursuant to Section 1.5.4 of the First Supplemental Indenture, state the amount: $        .

SCHEDULE OF EXCHANGES OF INTERESTS IN THE GLOBAL SECURITY

The following exchanges of a part of this Global Security for an interest in another Global Security or for a Definitive Security, or exchanges of a part of another Global Security or Definitive Security for an interest in this Global Security, have been made: