Exhibit 4.1

                        CERTIFICATE OF THE DESIGNATIONS,
                         POWERS, PREFERENCES AND RIGHTS
                                       OF
                      SERIES A CONVERTIBLE PREFERRED STOCK
                                       OF
                         iBEAM BROADCASTING CORPORATION

                        (Pursuant to Section 151 of the
                       Delaware General Corporation Law)

      iBEAM BROADCASTING CORPORATION, a Delaware corporation (the "Company"),
hereby certifies that the following resolution was adopted by the Board of
Directors of the Company:

      "RESOLVED, that pursuant to the authority expressly granted to and vested
in the Board of Directors of the Company (the "Board of Directors") by the
provisions of the Restated Certificate of Incorporation of the Company (the
"Certificate of Incorporation"), there is hereby created, out of the 10,000,000
shares of Preferred Stock, par value $0.0001 per share (the "Preferred Stock"),
of the Company authorized in Article Fourth of the Certificate of Incorporation,
a series of the Preferred Stock consisting of 3,000,000 shares, which series
shall have the following powers, designations, preferences and relative,
participating, optional or other rights, and the following qualifications,
limitations and restrictions (in addition to any powers, designations,
preferences and relative, participating, optional or other rights, and any
qualifications, limitations and restrictions, set forth in the Certificate of
Incorporation which are applicable to the Preferred Stock):

Section 1. Designation of Amount.

      The shares of Preferred Stock created hereby shall be designated the
"Series A Convertible Preferred Stock" (the "Series A Preferred Stock") and the
authorized number of shares constituting such series shall be 3,000,000.


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<PAGE>

Section 2. Ranking; Term.

      (a) The Series A Preferred Stock shall, with respect to dividend rights
and rights to distributions upon the liquidation, winding-up or dissolution of
the Company, rank senior to all classes of common stock, par value $0.0001 per
share, of the Company (the "Common Stock") and to each other class or series of
capital stock or other equity securities of the Company authorized, issued or
otherwise established; provided, however, that the authorization, issuance or
establishment of a series of Preferred Stock the terms of which rank senior to
or on a parity with the Series A Preferred Stock as to dividends and
distributions upon the liquidation, winding-up or dissolution of the Company may
be approved in accordance with the provisions of Section 9(b) hereof.

      (b) The Series A Preferred Stock shall be perpetual and may not be
redeemed, purchased, retired or otherwise acquired by the Company unless such
redemption, purchase, retirement or other acquisition by the Company is
expressly authorized herein and consummated in accordance with the provisions
specified herein; provided, however, that the Company may, with the written
consent of a holder of outstanding shares of Series A Preferred Stock, redeem,
purchase, retire or otherwise acquire any or all of the outstanding shares of
Series A Preferred Stock held by such holder at a price per share not less than
the Liquidation Preference (as hereinafter defined) thereof as of the intended
date of redemption, purchase, retirement or other acquisition.

Section 3. Dividends.

      (a) The holders of the then outstanding shares of Series A Preferred Stock
will be entitled to receive, when, as and if declared by the Board of Directors
out of funds of the Company legally available therefore, cumulative preferential
dividends, accruing on a daily basis from the original date of issuance of the
Series A Preferred Stock (the "Issue Date"), at the Dividend Rate (as
hereinafter defined) of the Liquidation Preference (as hereinafter defined) per
share of Series A Preferred Stock, payable quarterly on each April 15, July 15,
October 15 and January 15, to the holders of Series A Preferred Stock of record
as of the preceding March 31, June 30, September 30 and December 31, as the case
may be; provided, however, that if any such Dividend Payment Date is not a
Business Day then such dividend shall be payable on the next Business Day. The
dividends provided for in this Section 3(a) are hereinafter referred to as "Base
Dividends." For purposes hereof, "Business Day" means any day other then a
Saturday, Sunday or day on which banking institutions in the State of New York
or the State of California are authorized or required to remain closed.
"Dividend Rate" means 10% per annum. Dividends shall be payable at the Dividend
Rate in cash. All dividends paid with respect to shares of


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<PAGE>

Series A Preferred Stock pursuant to this Section 3 shall be made pro rata among
the holders of Series A Preferred Stock based upon the aggregate accrued but
unpaid Base Dividends on the shares held by each such holder. The first dividend
payment shall be payable on October 15, 2001 with respect to the period from the
Issue Date to September 30, 2001. The amount of Base Dividends per share of
Series A Preferred Stock for any full quarterly dividend period shall be
computed by multiplying the applicable Dividend Rate by the Liquidation
Preference per share and dividing the result by four. Dividends payable on the
Series A Preferred Stock shall be computed on the basis of a 360-day year
consisting of twelve 30-day months.

      (b) To the extent not paid pursuant to Section 3(a) above, Base Dividends
shall accumulate, whether or not there are funds legally available for the
payment of such dividends and whether or not dividends are declared. For all
purposes hereunder, dividends on the Series A Preferred Stock shall be treated
as if the same were paid on the relevant Dividend Payment Date, whether or not
the same were in fact so paid or declared.

      (c) In the case of shares of Series A Preferred Stock issued on the Issue
Date, dividends shall accrue and be cumulative from such date. In the case of
shares of Series A Preferred Stock issued as a dividend on shares of Series A
Preferred Stock, dividends shall accrue and be cumulative from the Dividend
Payment Date in respect of which such shares were issued or were scheduled to be
paid pursuant to Section 3(a) hereof as a dividend.

      (d) Each fractional share of Series A Preferred Stock outstanding (or
treated as outstanding pursuant to Section 3(b) hereof) shall be entitled to a
ratably proportionate amount of all dividends accruing with respect to each
outstanding or due to be issued and outstanding share of Series A Preferred
Stock pursuant to Section 3(a), and all such dividends with respect to such
outstanding fractional shares shall be cumulative and shall accrue (whether or
not declared) and shall be payable in the same manner and at such times as
provided for in Section 3(a) with respect to dividends on each outstanding or
due to be issued and outstanding share of Series A Preferred Stock. Each
fractional share of Series A Preferred Stock outstanding shall also be entitled
to a ratably proportionate amount of any other distributions made with respect
to each outstanding or due to be issued and outstanding share of Series A
Preferred Stock, and all such distributions shall be payable in the same manner
and at the same time as distributions on each outstanding or due to be issued
and outstanding share of Series A Preferred Stock.

      (e) Accrued but unpaid dividends with respect to the Series A Preferred
Stock for any past dividend periods may be declared by the Board of Directors
and


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<PAGE>

paid on any date fixed by the Board of Directors, whether or not a regular
Dividend Payment Date, to holders of record of Series A Preferred Stock on the
books of the Company on such record date as may be fixed by the Board of
Directors, which record date shall be no more than 60 days prior to the payment
date thereof.

      (f) If Base Dividends have not been paid in full and sums have not been
set apart in trust for the payment thereof upon the shares of Series A Preferred
Stock and the shares of any other series of capital stock of the Company ranking
on a parity as to dividends with the Series A Preferred Stock ("Parity Dividend
Stock"), all dividends declared upon shares of Series A Preferred Stock and upon
all Parity Dividend Stock shall be paid or declared pro rata so that in all
cases the amount of dividends paid or declared per share on the Series A
Preferred Stock and such Parity Dividend Stock shall bear to each other the same
ratio that unpaid dividends per share, including dividends in arrears, if any,
on the shares of Series A Preferred Stock and such other shares of Parity
Dividend Stock, bear to each other. Unless and until full Base Dividends on the
shares of Series A Preferred Stock in respect of all past quarterly dividend
periods have been paid, and sums representing the full amount of Base Dividends
on the shares of Series A Preferred Stock in respect of the then current
quarterly dividend period are paid or shall have been or are contemporaneously
set aside in trust for the payment thereof, (i) no dividends shall be paid or
declared or set aside for payment or other distribution upon the Common Stock or
any other capital stock of the Company ranking junior to the Series A Preferred
Stock as to dividends or as to distributions upon liquidation, dissolution or
winding up of the Company (other than in shares of, or warrants or rights to
acquire, solely capital stock of the Company ranking junior to the Series A
Preferred Stock both as to dividends and as to distributions upon liquidation,
dissolution or winding up of the Company ("Junior Stock"), which Junior Stock
shall include, without limitation, the Common Stock) and (ii) no shares of
capital stock of the Company ranking junior to or on a parity with the Series A
Preferred Stock as to dividends or as to distributions upon liquidation,
dissolution or winding up of the Company shall be redeemed, retired, purchased
or otherwise acquired for any consideration (or any payment made to or available
for a sinking fund for the redemption of any such shares) by the Company or any
Subsidiary (except by conversion into or exchange solely for shares of Junior
Stock). For purposes hereof, a "Subsidiary" shall mean any corporation,
association, partnership, limited liability company, joint venture or other
business entity (i) at least 50% of the outstanding voting securities of which
are at the time owned or controlled, directly or indirectly, by the Company or
(ii) with respect to which the Company possesses, directly or indirectly, the
power to direct or cause the direction of the affairs or management of such
person.


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<PAGE>

      (g) In addition to Base Dividends, in the event any dividends are declared
or paid or any other distribution is made on or with respect to the Common
Stock, subject to the provisions of Section 3(h) hereof, the holders of the
Series A Preferred Stock as of the record date established by the Board of
Directors for such dividend or distribution on the Common Stock shall be
entitled to receive as additional dividends (the "Additional Dividends") an
amount (whether in the form of cash, securities or other property) per share of
Series A Preferred Stock, as if the Series A Preferred Stock had been converted
into shares of Common Stock as of the date immediately prior to the date for
determining the holders of Common Stock entitled to receive such dividend or
distribution, equal to the amount (and in the form) of the dividends declared or
paid or distribution made on or with respect to each share of Common Stock, such
Additional Dividends to be payable on the same payment date as the dividend on
the Common Stock established by the Board of Directors. The record date for any
such Additional Dividends shall be the record date for the applicable dividend
or distribution on the Common Stock, and any such Additional Dividends shall be
payable to the persons in whose name the Series A Preferred Stock is registered
at the close of business on the applicable record date.

             (h) No dividend shall be paid or declared on any share of Common
Stock unless (i) a dividend, payable in the same consideration and manner, is
simultaneously paid or declared, as the case may be, on each share of Series A
Preferred Stock in an amount determined as set forth in paragraph (g) above,
(ii) full Base Dividends on the shares of Series A Preferred Stock in respect of
all past quarterly dividend periods have been paid, and sums representing the
full amount of Base Dividends on the shares of Series A Preferred Stock in
respect of the then current quarterly dividend period are paid or shall have
been or are contemporaneously set aside in trust for the payment thereof, and
(iii) full Additional Dividends on the shares of Series A Preferred Stock in
respect of all past declared dividends on the Common Stock have been paid. For
purposes hereof, the term "dividends" shall include any pro rata distribution by
the Company, out of funds of the Company legally available therefor, of cash,
property, securities (including, but not limited to, rights, warrants or
options) or other property or assets to the holders of the Common Stock or other
Junior Stock, whether or not paid out of capital, surplus or earnings; provided,
that the holders of the Series A Preferred Stock shall not be entitled to
receive dividends pari passu with the Common Stock to the extent that (i) the
holders of the Common Stock receive dividends of additional shares of Common
Stock or other securities or rights convertible into, or entitling the holder
thereof to receive directly or indirectly, additional shares of Common Stock
("Common Stock Equivalents") without payment of any consideration by such holder
for such additional shares of Common Stock or Common Stock Equivalents
(including the


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<PAGE>

additional shares of Common Stock issuable upon conversion thereof) and (ii) the
provisions of Section 10(d)(4) shall apply.

Section 4. Liquidation Preference.

      In the event of a liquidation, dissolution or winding up of the Company,
whether voluntary or involuntary (a "Liquidation"), the holders of the Series A
Preferred Stock then outstanding shall be entitled to receive out of the
available assets of the Company, whether such assets are stated capital or
surplus of any nature, an amount on such date equal to the greater of (i) $16.66
per share of Series A Preferred Stock plus the amount of any accrued and unpaid
Base Dividends as of such date and any declared but unpaid Additional Dividends
as of such date (the "Liquidation Preference") and (ii) the amount per share of
Series A Preferred Stock that the holders of Series A Preferred Stock would have
received had such holders converted the shares of Series A Preferred Stock into
Common Stock immediately prior to such Liquidation. Such payment shall be made
before any payment shall be made or any assets distributed to the holders of any
class or series of the Common Stock or any other class or series of the
Company's capital stock ranking junior as to liquidation rights to the Series A
Preferred Stock. Following payment to the holders of the Series A Preferred
Stock of the full preferential amounts described in the first sentence of this
Section 4, the remaining assets (if any) of the Company available for
distribution to stockholders of the Company shall be distributed, subject to the
rights of the holders of shares of any other series of Preferred Stock ranking
prior to the Common Stock as to distributions upon Liquidation, pro rata among
the holders of the Common Stock and any other shares of capital stock of the
Company ranking on a parity with the Common Stock as to distributions upon
Liquidation. If upon any Liquidation the assets available for payment of the
full preferential amounts described in the first sentence of this Section 4 are
insufficient to permit the payment to the holders of the Series A Preferred
Stock of the full preferential amounts described in the first sentence of this
Section 4, then all the remaining available assets shall be distributed among
the holders of the then outstanding Series A Preferred Stock pro rata according
to the number of then outstanding shares of Series A Preferred Stock held by
each holder thereof.

Section 5. Mandatory Redemption.

      On July 9, 2011 (the "Final Redemption Date"), the Company shall redeem
for cash all shares of Series A Preferred Stock that are then outstanding at a
redemption price per share equal to the Liquidation Preference thereof as of the
Final Redemption Date (the "Final Redemption Price"). Not more than sixty (60)
nor less than thirty (30) days prior to the Final Redemption Date, notice by
first class mail, postage prepaid, shall be given to each holder of record of
the Series A Preferred


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<PAGE>

Stock, at such holder's address, as it shall appear upon the stock register of
the Company on such date. Each such notice of redemption shall be irrevocable
and shall specify the date that is the Final Redemption Date, the Final
Redemption Price, the identification of the shares to be redeemed, the place or
places of payment and that payment will be made upon presentation and surrender
of the certificate(s) evidencing the shares of Series A Preferred Stock to be
redeemed. On or after the Final Redemption Date, each holder of shares of Series
A Preferred Stock shall surrender the certificate evidencing such shares to the
Company at the place designated in such notice and shall thereupon be entitled
to receive payment of the Final Redemption Price in the manner set forth in the
notice. If, on the Final Redemption Date, funds in cash in an amount sufficient
to pay the aggregate Final Redemption Price for all outstanding shares of Series
A Preferred Stock shall be available therefor and shall have been irrevocably
set aside and deposited with a bank or trust company in trust for purposes of
payment of such Final Redemption Price, then, notwithstanding that the
certificates evidencing any shares so called for redemption shall not have been
surrendered, the shares shall no longer be deemed outstanding, the holders
thereof shall cease to be stockholders, and all rights whatsoever with respect
to the shares so called for redemption (except the right of the holders to
receive the Final Redemption Price upon surrender of their certificates
therefor) shall terminate. If at the Final Redemption Date, the Company does not
have sufficient capital and surplus legally available to redeem all the
outstanding shares of Series A Preferred Stock, the Company shall take all
measures permitted under the Delaware General Corporation Law to increase the
amount of its capital and surplus legally available, and the Company shall
redeem as many shares of Series A Preferred Stock as it may legally redeem,
ratably from the holders thereof in proportion to the number of shares held by
them, and shall thereafter from time to time, as soon as it shall have funds
available therefor, redeem as many shares of Series A Preferred Stock as it
legally may until it has redeemed all of the outstanding shares of Series A
Preferred Stock.

Section 6. Change of Control Redemption.

      (a) A Liquidation shall be deemed to have occurred upon the occurrence of
any of the following events:

                  (i) the acquisition by any individual, entity or group (a
            "Person"), other than Williams Communications, LLC, a Delaware
            limited liability company, or its affiliates (collectively,
            "Williams"), including any "person" within the meaning of Section
            13(d)(3) or 14(d)(2) of the Securities Exchange Act of 1934, as
            amended (the "Exchange Act"), of beneficial ownership within the
            meaning of Rule


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<PAGE>

            13d-3 promulgated under the Exchange Act, of 35% or more of the
            combined voting power of the then outstanding securities of the
            Company entitled to vote generally in the election of directors (the
            "Outstanding Company Voting Securities");

                  (ii) during any period of two consecutive years, individuals
            who at the beginning of such period constituted the members of the
            Board of Directors (together with any new members of the Board of
            Directors whose election by the Board of Directors or whose
            nomination for election by the stockholders of the Company was
            approved by a vote of at least 60% of the members of the full Board
            of Directors then still in office who were either directors at the
            beginning of such two-year period or whose election or nomination
            was previously so approved) cease for any reason to constitute a
            majority of the Board of Directors then in office;

                  (iii) the consummation of a reorganization, recapitalization,
            merger or consolidation or similar transaction involving the Company
            (each, a "Corporate Transaction"), in each case pursuant to which
            the individuals or entities who were the respective beneficial
            owners of the Outstanding Company Voting Securities immediately
            prior to such Corporate Transaction do not or will not beneficially
            own, directly or indirectly, more than 50% of the combined voting
            power of the outstanding securities entitled to vote generally in
            the election of directors of the corporation or other entity
            resulting from such Corporate Transaction or the ultimate parent of
            such corporation or other entity; or

                  (iv) the sale or other disposition of all or substantially all
            of the assets of the Company in one transaction or series of related
            transactions (each of the transactions or series of transactions
            described in Sections 6(a)(i) through (iv) is referred to as a
            "Fundamental Transaction").

      (b) The Company shall give each holder of record of Series A Preferred
Stock written notice, at such holder's address as it shall appear upon the stock
register of the Company on such date, of such impending Fundamental Transaction
not later than (x) twenty (20) days prior to the stockholders' meeting (if any)
called to approve such transaction, or (y) twenty (20) days prior to the
intended date of consummation of such transaction (or as soon as practicable
after the Company has knowledge of the Fundamental Transaction if later than 20
days prior to the intended date of consummation of the Fundamental Transaction),
whichever is earlier, and


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<PAGE>

shall also notify such holders in writing of the consummation of such
transaction within three (3) days after consummation of the transaction. The
first of such notices shall describe (i) the material terms and conditions of
the impending Fundamental Transaction, (ii) that the Company shall be obligated
to redeem (the "Change of Control Redemption") all outstanding shares of the
Series A Preferred Stock at a redemption price equal to the Liquidation
Preference thereof as of the date of consummation of such transaction, and (iii)
the procedure the holders must follow in surrendering their shares of Series A
Preferred Stock for redemption. The Company shall also provide prompt written
notices to the holders of Series A Preferred Stock of any material modifications
to the terms of the Fundamental Transaction or termination of the Fundamental
Transaction.

      (c) Beginning on the second Business Day after consummation of the
Fundamental Transaction and upon proper surrender to the Company (or an agent
designated by the Company for such purpose) of shares of Series A Preferred
Stock, the Company shall redeem all shares of Series A Preferred Stock properly
surrendered in connection with the Change of Control Redemption and shall cause
payment to be made on such day (the "Change of Control Payment Date") in cash
for such shares of Series A Preferred Stock.

Section 7. Optional Redemption by Company.

      (a) At any time after July 9, 2006, the Company may, in accordance with
the provisions of Section 7(b) hereof, redeem all or any part of the then
outstanding shares of Series A Preferred Stock for cash at a redemption price
equal to the Liquidation Preference thereof as of such date.

      (b) In order to exercise its right of optional redemption, the Company
shall, not more than ninety (90) nor less than sixty (60) days prior to the
redemption date, give to each holder of record of the Series A Preferred Stock,
at such holder's address as it shall appear upon the stock register of the
Company on such date, notice by first class mail, postage prepaid. Each such
notice of redemption shall be irrevocable and shall specify the date that is the
redemption date (the "Optional Redemption Date"), the redemption price, the
identification of the shares to be redeemed, the place or places of payment and
that payment will be made upon presentation and surrender of the certificate(s)
evidencing the shares of Series A Preferred Stock to be redeemed.

      (c) The holders of the Series A Preferred Stock shall retain their right
to convert such shares pursuant to Section 10 hereof until the close of business
on the last Business Day preceding the Optional Redemption Date.


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<PAGE>

Section 8. Restricted Payments; Status of Redeemed Shares.

      (a) After the Optional Redemption Date, Change of Control Payment Date or
Final Redemption Date, unless and until the full redemption price for the shares
of Series A Preferred Stock to be redeemed has been paid to, or set aside in
trust with a bank or trust company, (i) no dividends or other distribution shall
be paid or declared or set aside for payment on any capital stock or other
securities of the Company or any Subsidiary (other than dividends payable in
Common Stock or Common Stock Equivalents), and (ii) no shares of capital stock
or other securities of the Company or any Subsidiary shall be redeemed, retired,
purchased or otherwise acquired for any consideration (or any payment made to or
available for a sinking fund for the redemption of any such shares) by the
Company or any Subsidiary.

      (b) Any shares of Series A Preferred Stock which shall at any time have
been redeemed pursuant to Sections 5, 6 or 7 hereof shall, after such
redemption, have the status of authorized but unissued shares of Preferred
Stock, without designation as to series.

Section 9. Voting Rights.

      (a) Except as otherwise provided by applicable law and in addition to any
voting rights provided by law, the holders of outstanding shares of the Series A
Preferred Stock:

                  (i) shall be entitled to vote together with the holders of the
            Common Stock as a single class on all matters submitted for a vote
            of holders of Common Stock;

                  (ii) shall have such other voting rights as are specified in
            the Certificate of Incorporation or as otherwise provided by
            Delaware law; and

                  (iii) shall be entitled to receive notice of any stockholders'
            meeting in accordance with the Certificate of Incorporation and
            By-laws of the Company.

            For purposes of the voting rights set forth in this Section 9(a),
each share of Series A Preferred Stock shall entitle the holder thereof to cast
one vote for each whole vote that such holder would be entitled to cast had such
holder converted its Series A Preferred Stock into shares of Common Stock as of
the date immediately prior to the record date for determining the stockholders
of the Company eligible to vote on any such matter.


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<PAGE>

      (b) So long as any shares of Series A Preferred Stock remain outstanding
and Williams Communications, LLC together with its affiliates beneficially own
at least 40% of Williams Communications, LLC's original investment in the Series
A Preferred Stock (either in the form of Series A Preferred Stock, the Common
Stock issuable upon conversion thereof, or a combination thereof), the Company
shall not, without the written consent or affirmative vote of the holders of at
least two-thirds of the outstanding shares of Series A Preferred Stock, (i)
amend, alter, repeal or waive, whether by merger, consolidation, combination,
reclassification or otherwise, any provisions of the Certificate of
Incorporation or By-laws of the Company (including the adoption of a new
provision thereof) if such amendment, alteration or repeal would adversely alter
or change the rights, preferences or privileges of the Series A Preferred Stock
or (ii) create, authorize or issue any class, series or shares of Preferred
Stock or any other class of capital stock or other security ranking either as to
payment of dividends or distribution of assets upon Liquidation (x) prior to the
Series A Preferred Stock, or (y) on a parity with the Series A Preferred Stock,
or (z) junior to the Series A Preferred Stock, if such junior securities may be
redeemed in any circumstance on or prior to the Final Redemption Date. The vote
of the holders of at least two-thirds of the outstanding shares of Series A
Preferred Stock, voting separately as one class, shall be necessary to adopt any
alteration, amendment or repeal of any provision of this Certificate of
Designation, in addition to any other vote of stockholders required by law.

Section 10. Conversion Rights.

      (a) General. Subject to and upon compliance with the provisions of this
Section 10, the holders of the shares of Series A Preferred Stock shall be
entitled, at their option, at any time to convert all or any such shares of
Series A Preferred Stock into a number of fully paid and non-assessable shares
(calculated as to each conversion to the nearest 1/100,000th of a share) of
Common Stock. The number of shares of Common Stock to which a holder of Series A
Preferred Stock shall be entitled upon conversion shall be determined by
dividing (x) the Liquidation Preference of such Series A Preferred Stock as of
the Conversion Date (as hereinafter defined) by (y) the Conversion Price in
effect at the close of business on the Conversion Date (determined as provided
in this Section 10).

      (b) Conversion Price. The conversion price (the "Conversion Price") shall
initially be $0.1666, subject to adjustment from time to time in accordance with
Section 10(d).

      (c) Fractions of Shares. Unless the holder of shares of Series A Preferred
Stock being converted specifies otherwise, the Company shall issue fractional
shares of Common Stock (carried out to seven decimal places) upon conversion of
shares of


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<PAGE>

Series A Preferred Stock. If more than one share of Series A Preferred Stock
shall be surrendered for conversion at one time by the same holder, the number
of full shares of Common Stock to be issued shall be computed on the basis of
the aggregate number of shares of Series A Preferred Stock so surrendered.
Instead of any fractional shares of Common Stock which would otherwise be
issuable upon conversion of any shares of Series A Preferred Stock, the Company
shall pay a cash adjustment in respect of such fractional share in an amount
equal to the product of such fraction multiplied by the Fair Market Value (as
hereinafter defined) of one share of Common Stock on the Conversion Date.

      (d) Adjustments to Conversion Price. The Conversion Price shall be subject
to adjustment from time to time as follows:

            (1) Upon Issuance of Common Stock. If the Company shall, at any time
      or from time to time after the Issue Date, issue any shares of Common
      Stock (other than an issuance of Common Stock as a dividend or in a split
      of or subdivision in respect of which the adjustment provided for in
      Section 10(d)(4) applies), options to purchase or rights to subscribe for
      Common Stock, securities by their terms convertible into or exchangeable
      for Common Stock, or options to purchase or rights to subscribe for such
      convertible or exchangeable securities (other than Excluded Stock (as
      hereinafter defined)) without consideration or for consideration per share
      less than either (x) the Conversion Price in effect immediately prior to
      such issuance or (y) the Fair Market Value per share of Common Stock
      immediately prior to such issuance, then such Conversion Price shall
      forthwith be lowered to a price equal to the price obtained by
      multiplying:

                  (a)   the Conversion Price in effect immediately prior to the
                        issuance of such Common Stock, options, rights or
                        securities by

                  (b)   a fraction of which (x) the denominator shall be the
                        number of shares of Common Stock outstanding on a fully
                        diluted basis immediately after such issuance and (y)
                        the numerator shall be the sum of (i) the number of
                        shares of Common Stock outstanding on a fully diluted
                        basis immediately prior to such issuance and (ii) the
                        number of additional shares of Common Stock which the
                        aggregate consideration for the number of shares of
                        Common Stock so offered would purchase at the greater of
                        the Conversion


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<PAGE>

                        Price or Fair Market Value per share of Common Stock.

      For purposes of this Section 10(d), "fully diluted basis" shall be
determined in accordance with the treasury stock method of computing fully
diluted earnings per share in accordance with GAAP.

            (2) For the purposes of any adjustment of a Conversion Price
      pursuant to paragraph (1) of this Section 10(d), the following provisions
      shall be applicable:

                  (i) In the case of the issuance of Common Stock for cash in a
            public offering or private placement, the consideration shall be
            deemed to be the amount of cash paid therefor after deducting
            therefrom any discounts, commissions or placement fees payable by
            the Company to any underwriter or placement agent in connection with
            the issuance and sale thereof.

                  (ii) In the case of the issuance of Common Stock for a
            consideration in whole or in part other than cash, the consideration
            other than cash shall be deemed to be the Fair Market Value thereof.

                  (iii) In the case of the issuance of options to purchase or
            rights to subscribe for Common Stock, securities by their terms
            convertible into or exchangeable for Common Stock, or options to
            purchase or rights to subscribe for such convertible or exchangeable
            securities (except for options to acquire Excluded Stock):

                  (a) The aggregate maximum number of shares of Common Stock
            deliverable upon exercise of such options to purchase or rights to
            subscribe for Common Stock shall be deemed to have been issued at
            the time such options or rights were issued and for a consideration
            equal to the consideration (determined in the manner provided in
            subparagraphs (i) and (ii) above), if any, received by the Company
            upon the issuance of such options or rights plus the minimum
            purchase price provided in such options or rights for the Common
            Stock covered thereby;

                  (b) The aggregate maximum number of shares of Common Stock
            deliverable upon conversion of or in exchange for any such
            convertible or exchangeable securities or upon the exercise of
            options to purchase or rights to subscribe for such convertible or
            exchange-


                                       13
<PAGE>

            able securities and subsequent conversion or exchange thereof shall
            be deemed to have been issued at the time such securities, options,
            or rights were issued and for a consideration equal to the
            consideration received by the Company for any such securities and
            related options or rights (excluding any cash received on account of
            accrued interest or accrued dividends), plus the additional
            consideration, if any, to be received by the Company upon the
            conversion or exchange of such securities or the exercise of any
            related options or rights (the consideration in each case to be
            determined in the manner provided in paragraphs (i) and (ii) above);

                  (c) On any change in the number of shares or exercise price of
            Common Stock deliverable upon exercise of any such options or rights
            or conversions of or exchanges for such securities, including a
            change resulting from the anti-dilution provisions thereof, the
            applicable Conversion Price shall forthwith be readjusted to such
            Conversion Price as would have been in effect at such time if such
            options, rights or securities still outstanding had provided for
            such changed number of underlying shares or changed exercise price,
            as the case may be, at the time initially granted, issued or sold;
            and

                  (d) No further adjustment of the Conversion Price adjusted
            upon the issuance of any such options, rights, convertible
            securities or exchangeable securities shall be made as a result of
            the actual issuance of Common Stock on the exercise of any such
            rights or options or any conversion or exchange of any such
            securities.

                  (e) Upon the expiration of any such options or rights, the
            termination of any such rights to convert or exchange or the
            expiration of any options or rights related to such convertible or
            exchangeable securities, the Conversion Price, to the extent in any
            way affected by or adjusted by reason of such options, rights or
            securities or options or rights related to such securities, shall be
            readjusted to reflect the issuance of only the number of shares of
            Common Stock (and convertible and exchangeable securities which
            remain outstanding) actually issued upon the exercise of such
            options or rights, upon the conversion or exchange of such
            securities or upon the exercise of the options or rights related to
            such securities.

            (3) Upon Acquisition of Common Stock. If the Company or any
      Subsidiary shall, at any time or from time to time after the Issue Date,
      directly or indirectly, redeem, purchase or otherwise acquire any shares
      of


                                       14
<PAGE>

      Common Stock, options to purchase or rights to subscribe for Common Stock,
      securities by their terms convertible into or exchangeable for Common
      Stock (other than shares of Series A Preferred Stock that are redeemed
      according to their terms), or options to purchase or rights to subscribe
      for such convertible or exchangeable securities, for a consideration per
      share greater than the Fair Market Value (plus, in the case of such
      options, rights, or securities, the additional consideration required to
      be paid to the Company upon exercise, conversion or exchange) per share of
      Common Stock immediately prior to such event, then the Conversion Price
      shall forthwith be lowered to a price equal to the price obtained by
      multiplying:

                  (a)   the Conversion Price in effect immediately prior to such
                        event by

                  (b)   a fraction of which (x) the denominator shall be the
                        Fair Market Value per share of Common Stock immediately
                        prior to such event and (y) the numerator shall be the
                        result of dividing:

                        a) (1) the product of (A) the number of shares of Common
                  Stock outstanding on a fully-diluted basis and (B) the Fair
                  Market Value per share of Common Stock, in each case
                  immediately prior to such event, minus (2) the aggregate
                  consideration paid by the Company in such event (plus, in the
                  case of such options, rights, or convertible or exchangeable
                  securities, the aggregate additional consideration to be paid
                  by the Company upon exercise, conversion or exchange), by

                        b) the number of shares of Common Stock outstanding on a
                  fully-diluted basis immediately after such event.

      (4) Upon Stock Dividends, Subdivisions or Splits. If, at any time after
the Issue Date, the number of shares of Common Stock outstanding is increased by
a stock dividend payable in shares of Common Stock or by a subdivision or
split-up of shares of Common Stock, then, following the record date for the
determination of holders of Common Stock entitled to receive such stock
dividend, or to be affected by such subdivision or split-up, the Conversion
Price shall be appropriately decreased so that the number of


                                       15
<PAGE>

shares of Common Stock issuable upon conversion of Series A Preferred Stock
shall be increased in proportion to such increase in outstanding shares.

      (5) Upon Combinations. If, at any time after the Issue Date, the number of
shares of Common Stock outstanding is decreased by a combination of the
outstanding shares of Common Stock into a smaller number of shares of Common
Stock, then, following the record date to determine shares affected by such
combination, the Conversion Price shall be appropriately increased so that the
number of shares of Common Stock issuable on conversion of each share of Series
A Preferred Stock shall be decreased in proportion to such decrease in
outstanding shares.

      (6) Upon Reclassifications, Reorganizations, Consolidations or Mergers.
Subject to the provisions of Section 6 hereof, in the event of any capital
reorganization of the Company, any reclassification of the stock of the Company
(other than a change in par value or from par value to no par value or from no
par value to par value or as a result of a stock dividend or subdivision,
split-up or combination of shares), or any consolidation or merger of the
Company with or into another corporation (where the Company is not the surviving
corporation or where there is a change in or distribution with respect to the
Common Stock), each share of Series A Preferred Stock shall after such
reorganization, reclassification, consolidation or merger be convertible into
the kind and number of shares of stock or other securities or property of the
Company or of the successor corporation resulting from such consolidation or
surviving such merger, if any, to which the holder of the number of shares of
Common Stock deliverable (immediately prior to the time of such reorganization,
reclassification, consolidation or merger) upon conversion of such Series A
Preferred Stock would have been entitled upon such reorganization,
reclassification, consolidation or merger. The provisions of this clause shall
similarly apply to successive reorganizations, reclassifications, consolidations
or mergers. Subject to the provisions of Section 6, the Company shall not effect
any such reorganization, reclassification, consolidation or merger unless, prior
to the consummation thereof, the successor corporation (if other than the
Company) resulting from such reorganization, reclassification, consolidation,
shall assume, by written instrument, the obligation to deliver to the holders of
the Series A Preferred Stock such shares of stock, securities or assets, which,
in accordance with the foregoing provisions, such holders shall be entitled to
receive upon such conversion.


                                       16
<PAGE>

      (7) Deferral in Certain Circumstances. In any case in which the provisions
of this Section 10(d) shall require that an adjustment shall become effective
immediately after a record date of an event, the Company may defer until the
occurrence of such event:

            (i) issuing to the holder of any Series A Preferred Stock converted
      after such record date and before the occurrence of such event the shares
      of capital stock issuable upon such conversion by reason of the adjustment
      required by such event and issuing to such holder only the shares of
      capital stock issuable upon such conversion before giving effect to such
      adjustments, and

            (ii) paying to such holder any amount in cash in lieu of fractional
      share of capital stock pursuant to Section 10(c) above;

provided, however, that the Company shall deliver to such holder an appropriate
instrument or due bills evidencing such holder's right to receive such
additional shares and such cash.

      (8) Exceptions. Section 10(d) shall not apply to: (i) any issuance of
Common Stock upon exercise of any warrants or options awarded to employees or
directors of the Company, which options or warrants are outstanding on the Issue
Date, pursuant to stock option plans of the Company in existence on the Issue
Date and pursuant to terms in effect on the Issue Date, without giving effect to
any amendment, alteration or modification thereof effected after the Issue Date,
(ii) any issuance of securities by the Company in underwritten public offerings,
(iii) any issuance of Common Stock upon conversion of the Series A Preferred
Stock, (iv) the issuance of shares of Common Stock or Preferred Stock issuable
upon the exercise of warrants to purchase such securities outstanding on the
Issue Date, (v) the issuance of shares of Common Stock issued or issuable after
due authorization of such issuance by the affirmative vote of at least
two-thirds of the then outstanding shares of Series A Preferred Stock, provided
that the shares of Common Stock are issued pursuant to the terms authorized by
such stockholder approval, or (vi) the issuance of shares of Common Stock
pursuant to the Company's 2000 Employee Stock Purchase Plan, in accordance with
the terms of such plan as in effect on the Issue Date and without giving effect
to any amendment, alteration or repeal of any of the terms of such plan or any
increase in the number of shares of Common Stock reserved for issuance under
such plan (collectively, the "Excluded Stock"). Notwithstanding the foregoing,
in the case of shares of Series A Preferred


                                       17
<PAGE>

Stock called for redemption, conversion rights will expire at the close of
business on the last Business Day preceding any redemption date unless the
Company defaults in making the payment due upon redemption.

      (e) Exercise of Conversion Privilege.

                  (i) To convert shares of Series A Preferred Stock, a holder
            must (A) surrender the certificate or certificates evidencing such
            holder's shares of Series A Preferred Stock to be converted, duly
            endorsed in a form satisfactory to the Company, at the office of the
            Company and (B) notify the Company at such office that such holder
            elects to convert shares of Series A Preferred Stock and the number
            of shares such holder wishes to convert. Such notice (the
            "Conversion Notice") referred to in clause (B) above shall be
            delivered substantially in the following form:

                      "NOTICE TO EXERCISE CONVERSION RIGHT

      The undersigned, being a holder of the Series A Convertible Preferred
Stock of iBeam Broadcasting Corporation irrevocably exercises the right to
convert ____________ outstanding shares of Series A Convertible Preferred Stock
on ___________, ____, into shares of Common Stock of iBeam Broadcasting
Corporation, in accordance with the terms of the shares of Series A Convertible
Preferred Stock, and directs that the shares issuable and deliverable upon the
conversion be issued and delivered in the denominations indicated below to the
registered holder hereof unless a different name has been indicated below.
Dated: [At least one Business Day prior to the date fixed for conversion]

Fill in for registration of
shares of Common Stock
if to be issued otherwise
than to the registered
holder:

Name

Address


                                       18
<PAGE>

Please print name and                                (Signature)
address, including postal
code number

Denominations:_________"

                  (ii) Series A Preferred Stock shall be deemed to have been
            converted immediately prior to the close of business on the day (the
            "Conversion Date") of surrender of such shares of Series A Preferred
            Stock for conversion in accordance with the foregoing provisions and
            at such time the rights of the holders of such shares of Series A
            Preferred Stock as holder shall cease, and the Person or Persons
            entitled to receive the Common Stock issuable upon conversion shall
            be treated for all purposes as the record holder or holders of such
            Common Stock as and after such time. As promptly as practicable on
            or after the Conversion Date, the Company shall issue and shall
            deliver at any office or agency of the Company maintained for the
            surrender of Series A Preferred Stock a certificate or certificates
            for the number of full shares of Common Stock issuable upon
            conversion, together with payment in lieu of any fraction of a
            share, as provided in Section 10(c).

                  (iii) In the case of any certificate evidencing shares of
            Series A Preferred Stock which is converted in part only, upon such
            conversion the Company shall execute and deliver a new certificate
            representing an aggregate number of shares of Series A Preferred
            Stock equal to the unconverted portion of such certificate.

      (f) Notice of Adjustment of Conversion Price. Whenever the Conversion
Price is adjusted as herein provided: (i) the Company shall compute the adjusted
Conversion Price in accordance with Section 10(d) and shall prepare a
certificate signed by the Treasurer or Chief Financial Officer of the Company
setting forth the adjusted Conversion Price and showing in reasonable detail the
facts upon which such adjustment is based, and such certificate shall forthwith
be filed at each office or agency maintained for such purpose or conversion of
shares of Series A Preferred Stock; and (ii) a notice stating that the
Conversion Price has been adjusted and setting forth the adjusted Conversion
Price shall forthwith be prepared by the Company, and as soon as practicable
after it is prepared, such notice shall be mailed


                                       19
<PAGE>

by the Company at its expense to all holders at their last addresses as they
shall appear in the stock register.

      (g) Notice of Certain Corporate Action. In case: (i) the Company shall
grant to the holders of its Common Stock rights or warrants to subscribe for or
purchase any shares of capital stock of any class; or (ii) of any
reclassification of the Common Stock, or of any consolidation, merger or share
exchange to which the Company is a party and for which approval of any
stockholders of the Company is required, or of the sale or transfer of all or
substantially all of the assets of the Company; or (iii) of the voluntary or
involuntary dissolution, liquidation or winding up of the Company; or (iv) the
Company or any Subsidiary shall commence a tender offer for all or a portion of
the outstanding shares of Common Stock (or shall amend any such tender offer to
change the maximum number of shares being sought or the amount or type of
consideration being offered therefor); then the Company shall cause to be filed
at each office or agency maintained for such purpose, and shall cause to be
mailed to all holders at their last addresses as they shall appear in the stock
register, at least 30 days prior to the applicable record, effective or
expiration date hereinafter specified, a notice stating (x) the date on which a
record is to be taken for the purpose of such dividend, distribution or granting
of rights or warrants, or, if a record is not to be taken, the date as of which
the holders of Common Stock of record who will be entitled to such dividend,
distribution, rights or warrants are to be determined, (y) the date on which
such reclassification, consolidation, merger, share exchange, sale, transfer,
dissolution, liquidation or winding up is expected to become effective, and the
date as of which it is expected that holders of Common Stock of record shall be
entitled to exchange their shares of Common Stock for securities, cash or other
property deliverable upon such reclassification, consolidation, merger, share
exchange, sale, transfer, dissolution, liquidation or winding up, or (z) the
date on which such tender offer commenced, the date on which such tender offer
is scheduled to expire unless extended, the consideration offered and the other
material terms thereof (or the material terms of the amendment thereto). Such
notice shall also set forth such facts with respect thereto as shall be
reasonably necessary to indicate the effect of such action on the Conversion
Price and the number, kind or class of shares or other securities or property
which shall be deliverable or purchasable upon the occurrence of such action or
deliverable upon conversion of the Series A Preferred Stock. Neither the failure
to give any such notice nor any defect therein shall affect the legality or
validity of any action described in clauses (i) through (iv) of this Section
10(g).

      (h) Company to Reserve Common Stock. The Company shall at all times
reserve and keep available, free from preemptive rights, out of the authorized
but unissued Common Stock or out of the Common Stock held in treasury, for the


                                       20
<PAGE>

purpose of effecting the conversion of Series A Preferred Stock, the full number
of shares of Common Stock then issuable upon the conversion of all outstanding
shares of Series A Preferred Stock.

      Before taking any action that would cause an adjustment reducing the
Conversion Price below the then par value (if any) of the shares of Common Stock
deliverable upon conversion of the Series A Preferred Stock or that would cause
the number of shares of Common Stock deliverable upon conversion of the Series A
Preferred Stock to exceed (when taken together with all other outstanding shares
of Common Stock) the number of shares of Common Stock that the Company is
authorized to issue, the Company will take any corporate action that, in the
opinion of its counsel, is necessary in order that the Company may validly and
legally issue the full number of fully paid and non-assessable shares of Common
Stock issuable upon conversion at such adjusted conversion price.

      (i) Taxes on Conversions. The Company will pay any and all original
issuance, transfer, stamp and other similar taxes that may be payable in respect
of the issue or delivery of shares of Common Stock on conversion of Series A
Preferred Stock pursuant hereto. The Company shall not, however, be required to
pay any tax which may be payable in respect of any transfer involved in the
issue and delivery of shares of Common Stock in a name other than that of the
holder of the share(s) of Series A Preferred Stock to be converted, and no such
issue or delivery shall be made unless and until the Person requesting such
issue has paid to the Company the amount of any such tax, or has established to
the reasonable satisfaction of the Company that such tax has been or will be
paid.

      (j) Cancellation of Converted Series A Preferred Stock. All Series A
Preferred Stock delivered for conversion shall be delivered to the Company to be
cancelled and shall have the status of authorized but unissued shares of
Preferred Stock, without designation as to series.

      (k) Certain Definitions. The following terms shall have the following
respective meanings herein:

                  "Fair Market Value" means, as to any security, the Twenty Day
         Average of the average closing prices of such security's sales on all
         domestic securities exchanges on which such security may at the time be
         listed, or, if there have been no sales on any such exchange on any
         day, the average of the highest bid and lowest asked prices on all such
         exchanges at the end of such day, or, if on any day such security is
         not so listed, the average of the representative bid and asked prices
         quoted on the NASDAQ Stock Market as of 4:00 P.M., New York City time,
         on such day, or, if on any day such security


                                       21
<PAGE>

            is not quoted on the NASDAQ Stock Market, the average of the highest
            bid and lowest asked prices on such day in the domestic
            over-the-counter market as reported by the National Quotation
            Bureau, Incorporated, or any similar or successor organization (and
            in each such case excluding any trades that are not bona fide,
            arm's-length transactions). If at any time such security is not
            listed on any domestic securities exchange or quoted on the NASDAQ
            Stock Market or the domestic over-the-counter market, the "Fair
            Market Value" of such security shall be determined in good faith
            jointly by the Board of Directors and Williams Communications, LLC;
            provided, that if the Board of Directors and Williams
            Communications, LLC are not able to mutually agree on the fair
            market value of such security, Williams Communications, LLC and the
            Board of Directors shall select an investment banking firm of
            national standing in the United States to determine such fair market
            value in as prompt a manner as practicable; provided, further, that
            if the Board of Directors and Williams Communications, LLC are not
            able to mutually agree on such investment banking firm, each of
            Williams Communications, LLC and the Board of Directors shall select
            an investment banking firm of national standing in the United
            States, which two investment banking firms shall mutually select a
            third investment banking firm to determine such fair market value in
            as prompt a manner as practicable.

                  "Twenty Day Average" means, with respect to any prices and in
            connection with the calculation of Fair Market Value, the average of
            such prices over the twenty Business Days ending on the Business Day
            immediately prior to the day as of which "Fair Market Value" is
            being determined.

Section 11. Dividend Received Deduction.

      For federal income tax purposes, the Company shall report distributions on
the Series A Preferred Stock as dividends, to the extent of the Company's
current and accumulated earnings and profits (as determined for federal income
tax purposes).

Section 12. Preemptive Rights.

      The holders of Series A Preferred Stock shall have the preemptive rights
set forth in Section 6.1 of the Stockholders Agreement, dated as of July 9,
2001, by and among the Company, Williams Communications, LLC and the other
parties thereto, as such agreement may be amended from time to time.


                                       22
<PAGE>

      IN WITNESS WHEREOF, the Company has caused this Certificate of
Designations to be signed by Peter Desnoes, its President and Chief Executive
Officer, this 6th day of July, 2001.


                                      By:/s/ Peter Desnoes
                                         ---------------------------
                                         Name: Peter Desnoes
                                         Title: President and Chief
                                         Executive Officer


                                       23