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                                                                     EXHIBIT 4.2

               CERTIFICATE OF DESIGNATION, PREFERENCES AND RIGHTS

                                       OF

                SERIES A PARTICIPATING CUMULATIVE PREFERRED STOCK

                                       OF

                              CENTRA SOFTWARE, INC.

         Pursuant to Section 151 of the General Corporation Law of the State of
Delaware, Centra Software, Inc. (the "Corporation"), a corporation organized and
existing under the General Corporation Law of the State of Delaware, in
accordance with the provisions of Section 103 thereof, DOES HEREBY CERTIFY:

         That, pursuant to the authority conferred upon the Board of Directors
of the Corporation by Paragraph B of Article FOURTH of the Amended and Restated
Certificate of Incorporation of the Corporation (the "Certificate of
Incorporation"), the Board of Directors of the Corporation on April 19, 2002,
adopted the following resolution creating a series of Preferred Stock designated
as Series A Participating Cumulative Preferred Stock:

         RESOLVED, that, pursuant to the authority vested in the Board of
Directors of the Corporation in accordance with the provisions of the
Certificate of Incorporation of the Corporation, a series of Preferred Stock of
the Corporation is hereby created and that the designation and number of shares
thereof and the voting powers, preferences and relative, participating, optional
and other special rights of the shares of such series, and the qualifications,
limitations or restrictions thereof are as follows:

         SECTION 1. Designation and Number of Shares. The shares of such series
shall be designated as "Series A Participating Cumulative Preferred Stock" (the
"Series A Preferred Stock"), par value $.001 per share. The number of shares
initially constituting the Series A Preferred Stock shall be 300,000; provided,
however, that, if more than a total of 300,000 shares of Series A Preferred
Stock shall be issuable upon the exercise of Rights (the "Rights") issued
pursuant to the Rights Agreement dated as of April 19, 2002, between the
Corporation and American Stock Transfer & Trust Company, a transfer agent, as
Rights Agent (the "Rights Agreement"), the Board of Directors of the
Corporation, pursuant to Section 151(g) of the General Corporation Law of the
State of Delaware, shall direct by resolution or resolutions that a certificate
be properly executed, acknowledged, filed and recorded, in accordance with the
provisions of Section 103 thereof, providing for the total number of shares of
Series A Preferred Stock authorized to be issued to be increased (to the extent
that the Certificate of Incorporation then permits) to the largest number of
whole shares (rounded up to the nearest whole number) issuable upon exercise of
such Rights.

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         SECTION 2.  Dividends or Distributions.

         (a) Subject to the prior and superior rights of the holders of shares
of any other series of Preferred Stock or other class of capital stock of the
Corporation ranking prior and superior to the shares of Series A Preferred Stock
with respect to dividends, the holders of shares of the Series A Preferred Stock
shall be entitled to receive, when, as and if declared by the Board of
Directors, out of the assets of the Corporation legally available therefor, (1)
quarterly dividends payable in cash on the last day of each fiscal quarter in
each year, or such other dates as the Board of Directors of the Corporation
shall approve (each such date being referred to herein as a "Quarterly Dividend
Payment Date"), commencing on the first Quarterly Dividend Payment Date after
the first issuance of a share or a fraction of a share of Series A Preferred
Stock, in the amount of $10.00 per whole share (rounded to the nearest cent)
less the amount of all cash dividends declared on the Series A Preferred Stock
pursuant to the following clause (2) since the immediately preceding Quarterly
Dividend Payment Date or, with respect to the first Quarterly Dividend Payment
Date, since the first issuance of any share or fraction of a share of Series A
Preferred Stock (the total of which shall not, in any event, be less than zero)
and (2) dividends payable in cash on the payment date for each cash dividend
declared on the Common Stock in an amount per whole share (rounded to the
nearest cent) equal to the Formula Number (as hereinafter defined) then in
effect times the cash dividends then to be paid on each share of Common Stock.
In addition, if the Corporation shall pay any dividend or make any distribution
on the Common Stock payable in assets, securities or other forms of noncash
consideration (other than dividends or distributions solely in shares of Common
Stock), then, in each such case, the Corporation shall simultaneously pay or
make on each outstanding whole share of Series A Preferred Stock a dividend or
distribution in like kind equal to the Formula Number then in effect times such
dividend or distribution on each share of the Common Stock. As used herein, the
"Formula Number" shall be 1,000; provided, however, that if at any time after
April 19, 2002, the Corporation shall (i) declare or pay any dividend on the
Common Stock payable in shares of Common Stock or make any distribution on the
Common Stock in shares of Common Stock, (ii) subdivide (by a stock split or
otherwise) the outstanding shares of Common Stock into a larger number of shares
of Common Stock or (iii) combine (by a reverse stock split or otherwise) the
outstanding shares of Common Stock into a smaller number of shares of Common
Stock, then in each such event the Formula Number shall be adjusted to a number
determined by multiplying the Formula Number in effect immediately prior to such
event by a fraction, the numerator of which is the number of shares of Common
Stock that are outstanding immediately after such event and the denominator of
which is the number of shares of Common Stock that are outstanding immediately
prior to such event (and rounding the result to the nearest whole number); and
provided further, that, if at any time after April 19, 2002, the Corporation
shall issue any shares of its capital stock in a merger, reclassification, or
change of the outstanding shares of Common Stock, then in each such event the
Formula Number shall be appropriately adjusted to reflect such merger,
reclassification or change so that each share of Series A Preferred Stock
continues to be the economic equivalent of a Formula Number of shares of Common
Stock prior to such merger, reclassification or change.

         (b) The Corporation shall declare a dividend or distribution on the
Series A Preferred Stock as provided in Section 2(a) immediately prior to or at
the same time it declares a dividend or distribution on the Common Stock (other
than a dividend or distribution solely in shares of Common Stock); provided,
however, that, in the event no dividend or distribution (other than a

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dividend or distribution in shares of Common Stock) shall have been declared on
the Common Stock during the period between any Quarterly Dividend Payment Date
and the next subsequent Quarterly Dividend Payment Date, a dividend of $10.00
per share on the Series A Preferred Stock shall nevertheless be payable on such
subsequent Quarterly Dividend Payment Date. The Board of Directors may fix a
record date for the determination of holders of shares of Series A Preferred
Stock entitled to receive a dividend or distribution declared thereon, which
record date shall be the same as the record date for any corresponding dividend
or distribution on the Common Stock.

         (c) Dividends shall begin to accrue and be cumulative on outstanding
shares of Series A Preferred Stock from and after the Quarterly Dividend Payment
Date next preceding the date of original issue of such shares of Series A
Preferred Stock; provided, however, that dividends on such shares which are
originally issued after the record date for the determination of holders of
shares of Series A Preferred Stock entitled to receive a quarterly dividend and
on or prior to the next succeeding Quarterly Dividend Payment Date shall begin
to accrue and be cumulative from and after such Quarterly Dividend Payment Date.
Notwithstanding the foregoing, dividends on shares of Series A Preferred Stock
which are originally issued prior to the record date for the determination of
holders of shares of Series A Preferred Stock entitled to receive a quarterly
dividend on the first Quarterly Dividend Payment Date shall be calculated as if
cumulative from and after the last day of the fiscal quarter next preceding the
date of original issuance of such shares. Accrued but unpaid dividends shall not
bear interest. Dividends paid on the shares of Series A Preferred Stock in an
amount less than the total amount of such dividends at the time accrued and
payable on such shares shall be allocated pro rata on a share-by-share basis
among all such shares at the time outstanding.

         (d) So long as any shares of the Series A Preferred Stock are
outstanding, no dividends or other distributions shall be declared, paid or
distributed, or set aside for payment or distribution, on the Common Stock
unless, in each case, the dividend required by this Section 2 to be declared on
the Series A Preferred Stock shall have been declared.

         (e) The holders of the shares of Series A Preferred Stock shall not be
entitled to receive any dividends or other distributions except as provided
herein.

     SECTION 3. Voting Rights. The holders of shares of Series A Preferred Stock
shall have the following voting rights:

         (a) Each holder of Series A Preferred Stock shall be entitled to a
number of votes equal to the Formula Number then in effect, for each share of
Series A Preferred Stock held of record on each matter on which holders of the
Common Stock or stockholders generally are entitled to vote, multiplied by the
maximum number of votes per share which any holder of the Common Stock or
stockholders generally then have with respect to such matter (assuming any
holding period or other requirement to vote a greater number of shares is
satisfied).

         (b) Except as otherwise provided herein or by applicable law, the
holders of shares of Series A Preferred Stock and the holders of shares of
Common Stock shall vote together as one class for the election of directors of
the Corporation and on all other matters submitted to a vote of stockholders of
the Corporation.

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         (c) If, at the time of any annual meeting of stockholders for the
election of directors, the equivalent of six quarterly dividends (whether or not
consecutive) payable on any share or shares of Series A Preferred Stock are in
default, the number of directors constituting the Board of Directors of the
Corporation shall be increased by two. In addition to voting together with the
holders of Common Stock for the election of other directors of the Corporation,
the holders of record of the Series A Preferred Stock, voting separately as a
class to the exclusion of the holders of Common Stock, shall be entitled at said
meeting of stockholders (and at each subsequent annual meeting of stockholders),
unless all dividends in arrears have been paid or declared and set apart for
payment prior thereto, to vote for the election of two directors of the
Corporation, the holders of any Series A Preferred Stock being entitled to cast
a number of votes per share of Series A Preferred Stock equal to the Formula
Number. Until the default in payments of all dividends which permitted the
election of said directors shall cease to exist, any director who shall have
been so elected pursuant to the next preceding sentence may be removed at any
time, either with or without cause, only by the affirmative vote of the holders
of the shares of Series A Preferred Stock at the time entitled to cast a
majority of the votes entitled to be cast for the election of any such director
at a special meeting of such holders called for that purpose, and any vacancy
thereby created may be filled by the vote of such holders. If and when such
default shall cease to exist, the holders of the Series A Preferred Stock shall
be divested of the foregoing special voting rights, subject to revesting in the
event of each and every subsequent like default in payments of dividends. Upon
the termination of the foregoing special voting rights, the terms of office of
all persons who may have been elected directors pursuant to said special voting
rights shall forthwith terminate, and the number of directors constituting the
Board of Directors shall be reduced by two. The voting rights granted by this
Section 3(c) shall be in addition to any other voting rights granted to the
holders of the Series A Preferred Stock in this Section 3.

         (d) Except as provided herein, in Section 11 or by applicable law,
holders of Series A Preferred Stock shall have no special voting rights and
their consent shall not be required (except to the extent they are entitled to
vote with holders of Common Stock as set forth herein) for authorizing or taking
any corporate action.

         SECTION 4.  Certain Restrictions.

         (a) Whenever quarterly dividends or other dividends or distributions
payable on the Series A Preferred Stock as provided in Section 2 are in arrears,
thereafter and until all accrued and unpaid dividends and distributions, whether
or not declared, on shares of Series A Preferred Stock outstanding shall have
been paid in full, the Corporation shall not

                  (i)  declare or pay dividends on, make any other distributions
         on, or redeem or purchase or otherwise acquire for consideration any
         shares of stock ranking junior (either as to dividends or upon
         liquidation, dissolution or winding up) to the Series A Preferred
         Stock;

                  (ii) declare or pay dividends on or make any other
         distributions on any shares of stock ranking on a parity (either as to
         dividends or upon liquidation, dissolution or winding up) with the
         Series A Preferred Stock, except dividends paid ratably on the Series A
         Preferred Stock and all such parity stock on which dividends are
         payable or in

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         arrears in proportion to the total amounts to which the holders of all
         such shares are then entitled;

                  (iii) redeem or purchase or otherwise acquire for
         consideration shares of any stock ranking on a parity (either as to
         dividends or upon liquidation, dissolution or winding up) with the
         Series A Preferred Stock; provided that the Corporation may at any time
         redeem, purchase or otherwise acquire shares of any such parity stock
         in exchange for shares of any stock of the Corporation ranking junior
         (either as to dividends or upon dissolution, liquidation or winding up)
         to the Series A Preferred Stock; or

                  (iv)  purchase or otherwise acquire for consideration any
         shares of Series A Preferred Stock, or any shares of stock ranking on a
         parity with the Series A Preferred Stock, except in accordance with a
         purchase offer made in writing or by publication (as determined by the
         Board of Directors) to all holders of such shares upon such terms as
         the Board of Directors, after consideration of the respective annual
         dividend rates and other relative rights and preferences of the
         respective series and classes, shall determine in good faith will
         result in fair and equitable treatment among the respective series or
         classes.

         (b)      The Corporation shall not permit any subsidiary of the
Corporation to purchase or otherwise acquire for consideration any shares of
stock of the Corporation unless the Corporation could, under paragraph (a) of
this Section 4, purchase or otherwise acquire such shares at such time and in
such manner.

         SECTION 5. Liquidation Rights. Upon the liquidation, dissolution or
winding up of the Corporation, whether voluntary or involuntary, no distribution
shall be made (1) to the holders of shares of stock ranking junior (either as to
dividends or upon liquidation, dissolution or winding up) to the Series A
Preferred Stock unless, prior thereto, the holders of shares of Series A
Preferred Stock shall have received an amount equal to the accrued and unpaid
dividends and distributions thereon, whether or not declared, to the date of
such payment, plus an amount equal to the greater of (x) $10.00 per whole share
or (y) an aggregate amount per share equal to the Formula Number then in effect
times the aggregate amount to be distributed per share to holders of Common
Stock or (2) to the holders of stock ranking on a parity (either as to dividends
or upon liquidation, dissolution or winding up) with the Series A Preferred
Stock, except distributions made ratably on the Series A Preferred Stock and all
other such parity stock in proportion to the total amounts to which the holders
of all such shares are entitled upon such liquidation, dissolution or winding
up.

         SECTION 6. Consolidation, Merger, etc. In case the Corporation shall
enter into any consolidation, merger, combination or other transaction in which
the shares of Common Stock are exchanged for or changed into other stock or
securities, cash or any other property, then in any such case the then
outstanding shares of Series A Preferred Stock shall at the same time be
similarly exchanged or changed into an amount per share equal to the Formula
Number then in effect times the aggregate amount of stock, securities, cash or
any other property (payable in kind), as the case may be, into which or for
which each share of Common Stock is exchanged or changed. In the event both this
Section 6 and Section 2 appear to apply to a transaction, this Section 6 will
control.

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         SECTION 7.  No Redemption; No Sinking Fund.

         (a) The shares of Series A Preferred Stock shall not be subject to
redemption by the Corporation or at the option of any holder of Series A
Preferred Stock; provided, however, that the Corporation may purchase or
otherwise acquire outstanding shares of Series A Preferred Stock in the open
market or by offer to any holder or holders of shares of Series A Preferred
Stock.

         (b) The shares of Series A Preferred Stock shall not be subject to or
entitled to the operation of a retirement or sinking fund.

         SECTION 8.  Ranking. The Series A Preferred Stock shall rank junior to
all other series of Preferred Stock of the Corporation, unless the Board of
Directors shall specifically determine otherwise in fixing the powers,
preferences and relative, participating, optional and other special rights of
the shares of such series and the qualifications, limitations and restrictions
thereof.

         SECTION 9.  Fractional Shares. The Series A Preferred Stock shall be
issuable upon exercise of the Rights issued pursuant to the Rights Agreement in
whole shares or in any fraction of a share that is one one-thousandth
(1/1,000th) of a share or any integral multiple of such fraction which shall
entitle the holder, in proportion to such holder's fractional shares, to receive
dividends, exercise voting rights, participate in distributions and to have the
benefit of all other rights of holders of Series A Preferred Stock. In lieu of
fractional shares, the Corporation, prior to the first issuance of a share or a
fraction of a share of Series A Preferred Stock, may elect (1) to make a cash
payment as provided in the Rights Agreement for fractions of a share other than
one one-thousandth (1/1,000th) of a share or any integral multiple thereof or
(2) to issue depository receipts evidencing such authorized fraction of a share
of Series A Preferred Stock pursuant to an appropriate agreement between the
Corporation and a depository selected by the Corporation; provided that such
agreement shall provide that the holders of such depository receipts shall have
all the rights, privileges and preferences to which they are entitled as holders
of the Series A Preferred Stock.

         SECTION 10. Reacquired Shares. Any shares of Series A Preferred Stock
purchased or otherwise acquired by the Corporation in any manner whatsoever
shall be retired and canceled promptly after the acquisition thereof. All such
shares shall upon their cancellation become authorized but unissued shares of
Preferred Stock, without designation as to series until such shares are once
more designated as part of a particular series by the Board of Directors
pursuant to the provisions of Paragraph B of Article FOURTH of the Certificate
of Incorporation.

         SECTION 11. Amendment. None of the powers, preferences and relative,
participating, optional and other special rights of the Series A Preferred Stock
as provided herein or in the Certificate of Incorporation shall be amended in
any manner which would alter or change the powers, preferences, rights or
privileges of the holders of Series A Preferred Stock so as to affect them
adversely without the affirmative vote of the holders of at least 66-2/3% of the
outstanding shares of Series A Preferred Stock, voting as a separate class;
provided, however, that no such amendment approved by the holders of at least
66-2/3% of the outstanding shares of Series A Preferred Stock shall be deemed to
apply to the powers, preferences, rights or privileges of any

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holder of shares of Series A Preferred Stock originally issued upon exercise of
the Rights after the time of such approval without the approval of such holder.

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         IN WITNESS WHEREOF, the Corporation has caused this Certificate to be
duly executed in its corporate name on this 19th day of April, 2002.

                                            CENTRA SOFTWARE, INC.


                                            By:    /s/ LEON NAVICKAS
                                                 ---------------------------
                                            Name: Leon Navickas
                                            Title:  Chief Executive Officer

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