Document:

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                                                                     EXHIBIT 4.5
                                                                  EXECUTION COPY

                          CONCORD COMMUNICATIONS, INC.

                     3.0% CONVERTIBLE SENIOR NOTES DUE 2023

                         REGISTRATION RIGHTS AGREEMENT

                                                        December 8, 2003

BEAR, STEARNS & CO. INC.
383 Madison Avenue
New York, New York 10179
Ladies and Gentlemen:

      Concord Communications, Inc., a Massachusetts corporation (the "Company"),
proposes to issue and sell to the initial purchaser named in the purchase
agreement (the "Initial Purchaser"), upon the terms set forth in such purchase
agreement dated December 2, 2003 (the "Purchase Agreement"), its 3.0%
Convertible Senior Notes due 2023 (the "Securities"). As an inducement to the
Initial Purchaser to enter into the Purchase Agreement and in satisfaction of a
condition to the obligations of the Initial Purchaser thereunder, the Company
agrees with the Initial Purchaser for the benefit of Holders (as defined herein)
from time to time of the Registrable Securities (as defined herein) as follows:

      1. Definitions.

      (a) Capitalized terms used herein without definition shall have the
meanings ascribed to them in the Purchase Agreement. As used in this Agreement,
the following defined terms shall have the following meanings:

      "Additional Interest" has the meaning assigned thereto in Section 7(a)
hereof.

      "Additional Shares" has the meaning assigned thereto in Section 7(a)
hereof.

      "Affiliate" of any specified person means any other person which, directly
or indirectly, is in control of, is controlled by, or is under common control
with such specified person. For purposes of this definition, control of a person
means the power, direct or indirect, to direct or cause the direction of the
management and policies of such person whether by contract or otherwise; and the
terms "controlling" and "controlled" have meanings correlative to the foregoing.

      "Applicable Amount" means, (i) with respect to the Securities, the
principal amount of the Securities and (ii) with respect to shares of Common
Stock issued upon conversion of the
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Securities pursuant to the Indenture, the principal amount of Securities that
would then be convertible into such number of shares.

      "Business Day" means each Monday, Tuesday, Wednesday, Thursday and Friday
that is not a day on which banking institutions in The City of New York are
authorized or obligated by law or executive order to close.

      "Commission" means the United States Securities and Exchange Commission,
or any other federal agency at the time administering the Exchange Act or the
Securities Act, whichever is the relevant statute for the particular purpose.

      "Common Stock" means the Company's common stock, par value $0.01 per
share.

      "DTC" means The Depository Trust Company.

      "Effectiveness Period" has the meaning assigned thereto in Section 2(b)(i)
hereof.

      "Effective Time" means the time at which the Commission declares any Shelf
Registration Statement effective or at which any Shelf Registration Statement
otherwise becomes effective.

      "Exchange Act" means the United States Securities Exchange Act of 1934, as
amended.

      "Holder" means any person that is the record owner of Registrable
Securities (and includes any person that has a beneficial interest in any
Registrable Security in book-entry form).

      "Indenture" means the Indenture, dated as of December 8, 2003, between the
Company and Wilmington Trust Company, pursuant to which the Securities are to be
issued, and as amended and supplemented from time to time in accordance with its
terms.

      "Issue Date" means the first date of original issuance of the Securities.

      "Majority of Holders" means Holders holding over 50% of the aggregate
principal amount of Registrable Securities outstanding.

      "Notice and Questionnaire" means a Notice of Registration Statement and
Selling Securityholder Election and Questionnaire substantially in the form of
Appendix A hereto.

      "Notice Holder" has the meaning assigned thereto in Section 3(a)(i)
hereof. The term "person" means an individual, partnership, limited liability
company, corporation, trust or unincorporated organization, or a government or
agency or political subdivision thereof.

      "Prospectus" means the prospectus included in any Shelf Registration
Statement, as amended or supplemented by any prospectus supplement with respect
to the terms of the offering of any portion of the Registrable Securities
covered by any Shelf Registration Statement and by

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all other amendments and supplements to such prospectus, including all material
incorporated by reference in such prospectus and all documents filed after the
date of such prospectus by the Company under the Exchange Act and incorporated
by reference therein.

      "Registrable Securities" means all or any portion of the Securities issued
from time to time under the Indenture in registered form and the shares of
Common Stock issuable upon conversion of such Securities until the earliest of:
(x) the date on which such security has been registered under the Securities Act
and disposed of pursuant to an effective registration statement, (y) the date
that is two years after the later of (1) the last date of original issuance of
the Securities and (2) the last date that the Company or any of its Affiliates
was the owner of such Securities (or any predecessor thereto), or such shorter
period of time as permitted by Rule 144(k) (or any successor rule or regulation)
under the Securities Act or any successor provisions thereunder or (z) its sale
to the public pursuant to Rule 144 (or any successor rule or regulation) under
the Securities Act.

      "Registration Default" has the meaning assigned thereto in Section 7(a)
hereof.

      "Securities Act" means the United States Securities Act of 1933, as
amended.

      "Shelf Registration" means a registration effected pursuant to Section 2
hereof.

      "Shelf Registration Statement" means a "shelf" registration statement
filed under the Securities Act providing for the registration of, and the sale
on a continuous or delayed basis by the Holders of, all of the Registrable
Securities pursuant to Rule 415 under the Securities Act and/or any similar rule
that may be adopted by the Commission, filed by the Company pursuant to the
provisions of Section 2 of this Agreement, including the Prospectus contained
therein, any amendments and supplements to such registration statement,
including post-effective amendments, and all exhibits and all material
incorporated by reference in such registration statement, and any additional
"shelf" registration statements filed under the Securities Act to permit the
registration and sale of Registrable Securities pursuant to Section 3(a)(ii)
hereof.

      "Suspension Period" has the meaning assigned thereto in Section 2(c)
hereof.

      "Trust Indenture Act" means the Trust Indenture Act of 1939, or any
successor thereto, and the rules, regulations and forms promulgated thereunder,
as the same shall be amended from time to time. The term "underwriter" means any
underwriter, or any person deemed to be an underwriter pursuant to the
Securities Act and Exchange Act and the respective rules and regulations
thereunder, as in effect at any relevant time, of Registrable Securities in
connection with an offering thereof under a Shelf Registration Statement.

      (a) Wherever there is a reference in this Agreement to a percentage of the
"principal amount" of Registrable Securities or to a percentage of Registrable
Securities, each share of Common Stock issued upon conversion of the Securities
shall represent a principal amount or percentage of Registrable Securities
determined based on a quotient, (i) the numerator of which

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shall be equal to the aggregate principal amount of Securities issued, less the
aggregate principal amount of Securities outstanding as of the date of
determination, and (ii) the denominator of which shall be equal to the aggregate
number of shares of Common Stock issued upon conversion of the Securities as of
the date of determination.

      2. Shelf Registration.

      (a) The Company shall, no later than 90 calendar days following the Issue
Date, file with the Commission a Shelf Registration Statement relating to the
offer and sale of the Registrable Securities by the Holders from time to time in
accordance with the methods of distribution elected by such Holders and,
thereafter, shall use its reasonable best efforts to cause such initial Shelf
Registration Statement to be declared effective under the Securities Act no
later than 210 calendar days following the Issue Date; provided, however, that
no Holder shall be entitled to be named as a selling securityholder in any Shelf
Registration Statement as of the date it is declared effective or to use the
Prospectus forming a part thereof for offers and resales of Registrable
Securities unless such Holder is a Notice Holder.

      (b) Subject to Section 2(c) hereof, the Company shall use its reasonable
best efforts:

            (i)   to keep any Shelf Registration Statement continuously
      effective, supplemented and amended as required by the provisions of
      Section 3(j) hereof, in order to permit the Prospectus forming a part
      thereof to be usable by Holders until the earlier of: (1) two years from
      the last date of original issuance of any Securities or (2) such shorter
      period ending on the date that (x) all of the Holders of Registrable
      Securities that are not Affiliates of the Company are able to sell all
      Registrable Securities immediately without restriction pursuant to Rule
      144(k) under the Securities Act or any successor rule thereto, (y) all
      Registrable Securities registered under the Shelf Registration Statements
      have been sold or (z) all Registrable Securities have ceased to be
      outstanding (such period being referred to herein as the "Effectiveness
      Period"); and

            (ii)  after the Effective Time of the initial Shelf Registration
      Statement, after the receipt of a completed and signed Notice and
      Questionnaire from any Holder of Registrable Securities that is not then a
      Notice Holder, to take the actions provided for in Section 3(a)(ii)
      hereof.

The Company shall be deemed not to have used its reasonable best efforts to keep
any Shelf Registration Statement effective during the Effectiveness Period if
the Company voluntarily takes any action that would result in Holders of
Registrable Securities covered thereby not being able to offer and sell any of
such Registrable Securities under such Shelf Registration Statement during that
period, unless such action is (A) required by applicable law and the Company
thereafter promptly complies with the requirements of Section 3(j) hereof or (B)
permitted pursuant to Section 2(c) hereof.

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      (c) After the Effective Time of the initial Shelf Registration Statement,
the Company may suspend the use of any Prospectus by written notice to the
Notice Holders for a period not to exceed an aggregate of 45 calendar days in
any 90 calendar day period (each such period, a "Suspension Period") if:

            (i)   an event has occurred and is continuing as a result of which
      the Shelf Registration Statement would, in the Company's judgment, contain
      an untrue statement of a material fact or omit to state a material fact
      required to be stated therein or necessary to make the statements therein
      not misleading; and

            (ii)  the Company determines in good faith that the disclosure of
      such event at such time would have a material adverse effect on the
      Company and its subsidiaries taken as a whole;

provided, that in the event the disclosure relates to a previously undisclosed
proposed or pending material business transaction, the disclosure of which would
impede the Company's ability to consummate such transaction, the Company may
extend a Suspension Period from 30 calendar days to 60 calendar days; provided,
however, that Suspension Periods (including, without limitation, any such
extension of a Suspension Period) shall not exceed an aggregate of 120 calendar
days in any 360 calendar day period.

      3. Registration Procedures. In connection with the Shelf Registration
Statements, the following provisions shall apply:

      (a)   (i)   Not less than 30 calendar days prior to the time the Company
      in good faith intends to have the initial Shelf Registration Statement
      declared effective, the Company shall distribute the Notice and
      Questionnaire to the Holders of Registrable Securities. The Company shall
      take action to name as a selling securityholder in the initial Shelf
      Registration Statement at the Effective Time each Holder that completes,
      executes and delivers a Notice and Questionnaire to the Company at the
      address set forth in the Notice and Questionnaire (a "Notice Holder")
      prior to or on the 20th calendar day after such Holder's receipt thereof
      so that such Holder is permitted to deliver the Prospectus forming a part
      thereof as of such time to purchasers of such Holder's Registrable
      Securities in accordance with applicable law. The Company shall not be
      required to take any action to name any Holder as a selling securityholder
      in the initial Shelf Registration Statement at the time of its
      effectiveness or to enable any Holder to use the Prospectus forming a part
      thereof for resales of Registrable Securities unless such Holder has
      returned a completed and signed Notice and Questionnaire to the Company in
      a timely manner.

            (ii)  After the Effective Time of the initial Shelf Registration
      Statement, the Company shall, upon the request of any Holder of
      Registrable Securities that is not then a Notice Holder, promptly send a
      Notice and Questionnaire to such Holder. After the Effective Time of the
      initial Shelf Registration Statement, the Company

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      shall (A) after the date a completed and signed Notice and Questionnaire
      is delivered to the Company, prepare and file with the Commission (x) a
      supplement to the Prospectus as promptly as practicable or, if required by
      applicable law, a post-effective amendment to the Shelf Registration
      Statement or an additional Shelf Registration Statement as promptly as
      practicable after the end of each fiscal quarter and (y) any other
      document required by applicable law, so that the Holder delivering such
      Notice and Questionnaire is named as a selling securityholder in a Shelf
      Registration Statement and is permitted to deliver the Prospectus to
      purchasers of such Holder's Registrable Securities in accordance with
      applicable law, and (B) if the Company shall file a post-effective
      amendment to the Shelf Registration Statement, or an additional Shelf
      Registration Statement, use its reasonable best efforts to cause such
      post-effective amendment or such additional Shelf Registration Statement
      to become effective under the Securities Act as promptly as is
      practicable; provided, however, that if a Notice and Questionnaire is
      delivered to the Company during a Suspension Period, the Company shall not
      be obligated to take the actions set forth in this clause (ii) until the
      termination of such Suspension Period.

      (b) The Company shall furnish to each Notice Holder, prior to the
Effective Time, a copy of the Shelf Registration Statement initially filed with
the Commission, and shall furnish to such Notice Holders, prior to the filing
with the Commission, copies of each amendment thereto and each amendment or
supplement, if any, to the Prospectus included therein (other than supplements
solely for the purpose of naming one or more Notice Holders as selling
securityholders), and shall use its best efforts to reflect in each such
document, at the Effective Time or when so filed with the Commission, as the
case may be, such comments as such Notice Holders and their respective counsel
reasonably may propose.

      (c) The Company shall promptly take such action as may be necessary so
that (i) each of the Shelf Registration Statements and any amendment thereto and
the Prospectus forming a part thereof and any amendment or supplement thereto
(and each report or other document incorporated therein by reference in each
case) complies in all material respects with the Securities Act and the Exchange
Act and the respective rules and regulations thereunder, as in effect at any
relevant time, (ii) each of the Shelf Registration Statements and any amendment
thereto does not, when it becomes effective, contain an untrue statement of a
material fact or omit to state a material fact required to be stated therein or
necessary to make the statements therein not misleading, and (iii) each of the
Prospectus forming a part of any Shelf Registration Statement, and any amendment
or supplement to such Prospectus, in the form delivered to purchasers of the
Registrable Securities during the Effectiveness Period, does not include an
untrue statement of a material fact or omit to state a material fact necessary
in order to make the statements therein, in the light of the circumstances under
which they were made, not misleading.

      (d) The Company shall promptly advise each Notice Holder, and shall
confirm such advice in writing if so requested by any such Notice Holder:

            (i)   when the initial Shelf Registration Statement has been filed
      with the Commission and when the initial Shelf Registration Statement has
      become effective, in each case making a public announcement thereof in a
      newspaper of general

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      circulation in The City of New York or by publishing the information on
      the Company's website or through such other broad, public medium as the
      Company may see fit;

            (ii)  when any Prospectus supplement, Shelf Registration Statement
      or post-effective amendment to a Shelf Registration has been filed with
      the Commission and, with respect to a Shelf Registration Statement or any
      post-effective amendment, when the same has been declared effective by the
      Commission;

            (iii) of any request by the Commission for amendments or supplements
      to any Shelf Registration Statement or the Prospectus included therein or
      for additional information;

            (iv)  of the issuance by the Commission of any stop order suspending
      the effectiveness of any Shelf Registration Statement or the initiation of
      any proceedings for such purpose;

            (v)   of the receipt by the Company of any notification with respect
      to the suspension of the qualification of the securities included in any
      Shelf Registration Statement for sale in any jurisdiction or the
      initiation of any proceeding for such purpose; and

            (vi)  of the happening of any event or the existence of any state of
      facts that requires the making of any changes in any Shelf Registration
      Statement or the Prospectus included therein so that, as of such date,
      such Shelf Registration Statement and Prospectus do not contain an untrue
      statement of a material fact and do not omit to state a material fact
      required to be stated therein or necessary to make the statements therein
      (in the case of the Prospectus, in the light of the circumstances under
      which they were made) not misleading (which advice shall be accompanied by
      an instruction to such Holders to suspend the use of the Prospectus until
      the requisite changes have been made, which notice need not specify the
      nature of the event giving rise to such suspension).

      (e) The Company shall use its best efforts to prevent the issuance, and if
issued to obtain the withdrawal at the earliest possible time, of any order
suspending the effectiveness of any Shelf Registration Statement.

      (f) As promptly as reasonably practicable furnish to each Notice Holder,
upon their request and without charge, at least one (1) conformed copy of the
Registration Statement and any amendment thereto, including financial statements
but excluding schedules, all documents incorporated or deemed to be incorporated
therein by reference and all exhibits (unless requested in writing to the
Company by such Notice Holder).

      (g) The Company shall, during the Effectiveness Period, deliver to each
Notice Holder, without charge, as many copies of each Prospectus in which the
Notice Holder is listed as a selling securityholder included in the applicable
Shelf Registration Statement and any amendment or supplement thereto as such
Notice Holder may reasonably request; and the

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Company consents (except during a Suspension Period or during the continuance of
any event described in Section 3(d) (iii)-(vi) above) to the use of the
Prospectus and any amendment or supplement thereto by each of the Notice Holders
in connection with the offering and sale of the Registrable Securities covered
by the Prospectus and any amendment or supplement thereto during the
Effectiveness Period.

      (h) Prior to any offering of Registrable Securities pursuant to a Shelf
Registration Statement, the Company shall (i) register or qualify or cooperate
with the Notice Holders and their respective counsel in connection with the
registration or qualification (or exemption from such registration or
qualification) of such Registrable Securities for offer and sale under the
securities or "blue sky" laws of such jurisdictions within the United States as
any Notice Holder may reasonably request in writing, (ii) keep such
registrations or qualifications or exemption therefrom in effect and comply with
such laws so as to permit the continuance of offers and sales in such
jurisdictions for so long as may be necessary to enable any Notice Holder or
underwriter, if any, to complete its distribution of Registrable Securities
pursuant to such Shelf Registration Statement, and (iii) take any and all other
actions necessary or advisable to enable the disposition in such jurisdictions
of such Registrable Securities; provided, however, that in no event shall the
Company be obligated to (A) qualify as a foreign corporation or as a dealer in
securities in any jurisdiction where it would not otherwise be required to so
qualify but for this Section 3(h) or (B) subject itself to general or unlimited
service of process or to taxation in any such jurisdiction if they are not now
so subject.

      (i) Unless any Registrable Securities shall be in book-entry only form,
the Company shall cooperate with the Notice Holders to facilitate the timely
preparation and delivery of certificates representing Registrable Securities to
be sold pursuant to any Shelf Registration Statement, which certificates, if so
required by any securities market or exchange upon which any Registrable
Securities are quoted or listed, shall be penned, lithographed or engraved, or
produced by any combination of such methods, on steel engraved borders, and
which certificates shall be free of any restrictive legends and in such
permitted denominations and registered in such names as Notice Holders may
request in connection with the sale of Registrable Securities pursuant to such
Shelf Registration Statement.

      (j) Upon the occurrence of any fact or event contemplated by paragraph
3(d)(vi) above, subject to Section 2(c) hereof, the Company shall promptly, but
in any event within 10 Business Days following such occurrence, prepare, file
(and have declared effective) a post-effective amendment to any Shelf
Registration Statement or an amendment or supplement to the related Prospectus
included therein or file any other document with the Commission so that, as
thereafter delivered to purchasers of the Registrable Securities, the Prospectus
will not include an untrue statement of a material fact or omit to state any
material fact necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading. If the Company
notifies the Notice Holders of the occurrence of any fact or event contemplated
by paragraph 3(d)(vi) above, the Notice Holder shall suspend the use of the
Prospectus until the requisite changes to the Prospectus have been made.

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      (k) Not later than the Effective Time of a Shelf Registration Statement,
the Company shall provide a CUSIP number for the debt securities to be sold
pursuant to a Shelf Registration Statement.

      (l) The Company shall use its best efforts to comply with the Securities
Act and the Exchange Act and the respective rules and regulations thereunder, as
in effect at any relevant time, and make generally available to its
securityholders earnings statements (which need not be audited) satisfying the
provisions of Section 11(a) of the Securities Act and Rule 158 thereunder (or
any similar rule promulgated under the Securities Act) no later than 45 days
after the end of any 12-month period (or 90 days after the end of any 12-month
period if such period is a fiscal year), or such shorter period as required by
the Securities Act and the Exchange Act and the rules and regulations
thereunder, as in effect at any relevant time, commencing on the first day of
the first fiscal quarter of the Company commencing after (i) the effective date
of a Shelf Registration Statement, (ii) the effective date of each
post-effective amendment to such Shelf Registration Statement, or (iii) the date
of each filing by the Company with the Commission of an Annual Report on Form
10-K that is incorporated by reference in such Shelf Registration Statement,
which statements shall cover said 12-month periods.

      (m) Not later than the Effective Time of the initial Shelf Registration
Statement, the Company shall use its best efforts to cause the Indenture to be
qualified under the Trust Indenture Act; in connection with such qualification,
the Company shall cooperate with the Trustee under the Indenture and the Holders
(as defined in the Indenture) to effect such changes to the Indenture as may be
required for such Indenture to be so qualified in accordance with the terms of
the Trust Indenture Act; and the Company shall execute, and shall use all
reasonable efforts to cause the Trustee to execute, all documents that may be
required to effect such changes and all other forms and documents required to be
filed with the Commission to enable such Indenture to be so qualified in a
timely manner. In the event that any such amendment or modification referred to
in this Section 3(m) involves the appointment of a new trustee under the
Indenture, the Company shall appoint a new trustee thereunder pursuant to the
applicable provisions of the Indenture.

      (n) The Company shall enter into such customary agreements and take all
such other necessary actions in connection therewith (including those reasonably
requested by the holders of a majority of the Registrable Securities being sold)
in order to expedite or facilitate disposition of such Registrable Securities;
provided, that the Company shall not be required to take any action in
connection with an underwritten offering without its consent.

      (o) The Company shall make reasonably available for inspection by one or
more representatives of the selling Holders, designated in writing by a Majority
of Holders whose Registrable Securities are included in a Shelf Registration
Statement, any underwriter participating in any disposition pursuant to any
Shelf Registration Statement, and any attorney, accountant or other agent
retained by such Notice Holders or any such underwriter all relevant financial
and other records, pertinent corporate documents and properties of the Company
and its subsidiaries, and (B) cause the Company's officers, directors and
employees to make reasonably available for inspection all information reasonably
requested by such Notice Holders or any such underwriter, attorney, accountant
or agent in connection with such Shelf Registration Statement, in each case, as
is customary for similar due diligence examinations; provided, however, that

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such persons shall, at the Company's request, first agree in writing with the
Company that any information that is reasonably and in good faith designated by
the Company in writing as confidential at the time of delivery, or inspection,
as the case may be, of such information shall be kept confidential by such
persons and shall be used solely for the purposes of exercising rights under
this Agreement, unless such disclosure is made in connection with a court
proceeding or required by law, or such records, information or documents become
available to the public generally or through a third party without an
accompanying obligation of confidentiality; and provided further that, if the
foregoing inspection and information gathering would otherwise disrupt the
Company's conduct of its business, such inspection and information gathering
shall, to the greatest extent possible, be coordinated on behalf of the Notice
Holders and the other parties entitled thereto by one counsel designated by and
on behalf of the Notice Holders and other parties.

      (p) The Company will use its best efforts to cause the Common Stock
issuable upon conversion of the Securities to be quoted or listed on the Nasdaq
National Market or other market or stock exchange on which the Common Stock
primarily trades on or prior to the Effective Time of each Shelf Registration
Statement hereunder.

      (q) The Company will cooperate and assist in any filings required to be
made with National Association of Securities Dealers, Inc.

      (r) The Company shall use its best efforts to take all other steps
necessary to effect the registration, offering and sale of the Registrable
Securities covered by each Shelf Registration Statement contemplated hereby.

      4. Registration Expenses. The Company shall bear all fees and expenses
incurred in connection with the performance by the Company of its obligations
under Sections 2 and 3 of this Agreement whether or not any of the Shelf
Registration Statements are declared effective. Such fees and expenses shall
include, without limitation, (i) all registration and filing fees (including,
without limitation, fees and expenses (x) with respect to filings required to be
made with the National Association of Securities Dealers, Inc. and (y) of
compliance with United States federal and state securities or Blue Sky laws to
the extent such filings or compliance are required pursuant to this Agreement
(including, without limitation, reasonable fees and disbursements of the counsel
specified in the next sentence in connection with Blue Sky qualifications of the
Registrable Securities under the laws of such jurisdictions as the Notice
Holders of a majority of the Registrable Securities being sold pursuant to a
Shelf Registration Statement may designate)), (ii) printing expenses (including,
without limitation, expenses of printing certificates for Registrable Securities
in a form eligible for deposit with The Depository Trust Company), (iii)
duplication expenses relating to copies of any Shelf Registration Statement or
Prospectus delivered to any Holders hereunder, (iv) fees and disbursements of
counsel for the Company in connection with the Shelf Registration Statement, and
(v) reasonable fees and disbursements of the Trustee and its counsel and of the
registrar and transfer agent for the Common Stock. In addition, the Company
shall bear or reimburse the Notice Holders for the reasonable fees and
disbursements of one firm of legal counsel for the Holders, which shall
initially be counsel to the Initial Purchaser, but which may, upon the written
consent of the Initial Purchaser (which shall not be unreasonably withheld), be
another nationally recognized law firm

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experienced in securities law matters designated by the Company. In addition,
the Company shall pay the internal expenses of the Company (including, without
limitation, all salaries and expenses of officers and employees performing legal
or accounting duties), the expense of any annual audit, the fees and expenses
incurred in connection with the listing of the Registrable Securities on any
securities exchange on which similar securities of the Company are then listed
and the fees and expenses of any person, including special experts, retained by
the Company.

      5. Indemnification and Contribution.

      (a) Indemnification by the Company. The Company shall indemnify and hold
harmless each Notice Holder, the Initial Purchaser, and each person, if any, who
controls any such Notice Holder or Initial Purchaser within the meaning of
Section 15 of the Securities Act or Section 20 of the Exchange Act, from and
against any loss, claim, damage, liability or expense whatsoever as incurred
(including but not limited to reasonable attorneys' fees and any and all
expenses whatsoever incurred in investigating, preparing or defending against
any litigation, commenced or threatened, or any claim whatsoever, and any and
all amounts paid in settlement of any claim or litigation), joint or several, to
which they or any of them may become subject under the Securities Act, the
Exchange Act or otherwise, insofar as any such loss, claim, damage, liability or
expense (or action in respect thereof) arises out of, or is based upon, any
untrue statement or alleged untrue statement of a material fact contained in the
Shelf Registration Statement or any amendment thereto or any related preliminary
prospectus or the Prospectus or any amendment thereto of supplement thereof, or
arises out of, or is based upon, the omission or alleged omission to state
therein any material fact required to be stated therein or necessary to make the
statements therein not misleading; provided, however, that the Company shall not
be liable to any such indemnified party in any such case to the extent that any
such loss, claim, damage, liability or expense arises out of, or is based upon,
any such untrue statement or alleged untrue statement or omission or alleged
omission made therein in reliance upon and in conformity with written
information furnished to the Company by or on behalf of such indemnified party
specifically for use therein; and provided further, however, that the Company
shall not be liable to any such indemnified party in any such case to the extent
that such loss, claim, damage, liability or expense arises from an offer or sale
by a Notice Holder of Registrable Securities during a Suspension Period, if such
indemnified party is a Notice Holder that received from the Company a notice of
the commencement of such Suspension Period prior to the making of such offer or
sale. The foregoing indemnity agreement is in addition to any liability that the
Company may otherwise have to any indemnified party. The Company shall not be
liable under this Section 5(a) for any settlement of any action effected without
its written consent, which shall not be unreasonably withheld, provided,
however, that with respect to actions pursuant to clauses (1), (2) and (3) of
Section 5(c), no such consent shall be required.

      (b) Indemnification by the Notice Holders. Each Notice Holder, severally
and not jointly, shall indemnify and hold harmless the Company, the Initial
Purchaser, and each person, if any, who controls the Company or the Initial
Purchaser within the meaning of Section 15 of the Securities Act or Section 20
of the Exchange Act, from and against any loss, claim, damage, liability or
expense whatsoever as incurred (including but not limited to attorneys' fees and
any and all expenses whatsoever incurred in investigating, preparing or
defending against any litigation, commenced or threatened, or any claim
whatsoever, and any and all amounts paid in

                                       11
<PAGE>
settlement of any claim or litigation), joint or several, to which they or any
of them may become subject under the Securities Act, the Exchange Act or
otherwise, insofar as any such loss, claim, damage, liability or expense (or
action in respect thereof) arises out of, or is based upon, any untrue statement
or alleged untrue statement of a material fact contained in the Shelf
Registration Statement or any amendment thereto or any related preliminary
prospectus or the Prospectus or any amendment thereto of supplement thereof, or
arises out of, or is based upon, the omission or alleged omission to state
therein any material fact required to be stated therein or necessary to make the
statements therein not misleading, in each case to the extent, but only to the
extent, that such untrue statement or alleged untrue statement or omission or
alleged omission made therein was made in reliance upon and in conformity with
written information furnished to the Company by or on behalf of such Notice
Holder specifically for use therein. In no event shall the liability of any
selling Notice Holder hereunder be greater in amount than the dollar amount of
the proceeds received by such Holder upon the sale of the Registrable Securities
pursuant to the Shelf Registration Statement giving rise to such indemnification
obligation. The foregoing indemnity agreement is in addition to any liability
that any Notice Holder may otherwise have to the Company, the Initial Purchaser
and any such controlling person.

      (c) Notices of Claims, Etc. Promptly after receipt by an indemnified party
under this Section 5 of notice of any claim or the commencement of any action,
the indemnified party shall, if a claim in respect thereof is to be made against
the indemnifying party under this Section 5, notify the indemnifying party in
writing of the claim or the commencement of that action; provided, however, that
the failure to notify the indemnifying party shall not relieve it from any
liability that it may have under this Section 5. If any such claim or action
shall be brought against an indemnified party, and it shall notify the
indemnifying party thereof, the indemnifying party shall be entitled to
participate therein and, to the extent that it wishes, jointly with any other
similarly notified indemnifying party, to assume the defense thereof with
counsel satisfactory to the indemnified party. After notice from the
indemnifying party to the indemnified party of its election to assume the
defense of such claim or action, the indemnifying party shall not be liable to
the indemnified party under this Section 5 for any legal or other expenses
subsequently incurred by the indemnified party in connection with the defense
thereof other than reasonable costs of investigation; provided, however, that
the indemnified party shall have the right to employ counsel to represent
jointly the indemnified party and its respective directors, employees, officers
and controlling persons who may be subject to liability arising out of any claim
in respect of which indemnity may be sought by the indemnified party against the
indemnifying party under this Section 5 if (1) employment of such counsel has
been authorized in writing by the indemnifying party, or (2) such indemnifying
party shall not have employed counsel to have charge of the defense of such
proceeding within 30 days of the receipt of notice thereof, or (3) such
indemnified party shall have reasonably concluded that the representation of
such indemnified party and those directors, employees, officers and controlling
persons by the same counsel representing the indemnifying party would be
inappropriate under applicable standards of professional conduct due to actual
or potential differing interests between them or where there may be one or more
defenses available to them that are different from, additional to or in conflict
with those available to the indemnifying party, and in any such event ((1), (2)
or (3)) the fees and expenses of such separate counsel shall be paid by the
indemnifying party as incurred. It is understood that the indemnifying party
shall not be liable for the fees and expenses of more than

                                       12
<PAGE>
one separate firm (in addition to local counsel in each jurisdiction) for all
indemnified parties in connection with any proceeding or related proceedings. No
indemnifying party shall, without the prior written consent of the indemnified
parties, effect any settlement or compromise of, or consent to the entry of
judgment with respect to, any pending or threatened claim, investigation, action
or proceeding in respect of which indemnity or contribution may be or could have
been sought hereunder (whether or not the indemnified party or parties are
actual or potential parties thereto) unless (x) such settlement, compromise or
judgment (i) includes an unconditional release of such indemnified party from
all liability arising out of such claim, action, suit or proceeding and (ii)
does not include a statement as to or an admission of fault, culpability or
failure to act by or on behalf of any indemnified party, and (y) the
indemnifying party confirms in writing its indemnification obligations hereunder
with respect to such settlement, compromise or judgment.

      (d) Contribution. If the indemnification provided for in this Section 5 is
unavailable or insufficient to hold harmless an indemnified party under
subsections (a) or (b) above, then each indemnifying party shall contribute to
the amount paid or payable by such indemnified party as a result of the losses,
claims, damages, expenses or liabilities (or actions in respect thereof)
referred to in subsection (a) or (b) above (i) in such proportion as is
appropriate to reflect the relative benefits received by the indemnifying party
or parties on the one hand and the indemnified party on the other from the
registration of the Registrable Securities pursuant to the Shelf Registration,
or (ii) if the allocation provided by the foregoing clause (i) is not permitted
by applicable law, in such proportion as is appropriate to reflect not only the
relative benefits referred to in clause (i) above but also the relative fault of
the indemnifying party or parties on the one hand and the indemnified party on
the other in connection with the statements or omissions that resulted in such
losses, claims, damages or liabilities (or actions in respect thereof) as well
as any other relevant equitable considerations. The relative fault of the
parties shall be determined by reference to, among other things, whether the
untrue or alleged untrue statement of a material fact or the omission or alleged
omission to state a material fact relates to information supplied by the Company
on the one hand or such Holder or such other indemnified party, as the case may
be, on the other, and the parties' relative intent, knowledge, access to
information and opportunity to correct or prevent such statement or omission.
The amount paid by an indemnified party as a result of the losses, claims,
damages or liabilities referred to in the first sentence of this subsection (d)
shall be deemed to include any legal or other expenses reasonably incurred by
such indemnified party in connection with investigating or defending any action
or claim which is the subject of this subsection (d). The Company and the
Holders agree that it would not be just and equitable if contribution pursuant
to this Section 5(d) were determined by pro rata allocation or by any other
method of allocation which does not take account of the equitable considerations
referred to herein. Notwithstanding any other provision of this Section 5(d),
the Holders of the Registrable Securities shall not be required to contribute
any amount in excess of the amount by which the gross proceeds received by such
Holders from the sale of the Registrable Securities pursuant to the Shelf
Registration Statement exceeds the amount of damages which such Holders have
otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission. No person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act)
shall be entitled to contribution from any person who was not guilty of such
fraudulent misrepresentation. For purposes of this paragraph (d), each person,
if any, who controls such indemnified party

                                       13
<PAGE>
within the meaning of the Securities Act or the Exchange Act shall have the same
rights to contribution as such indemnified party and each person, if any, who
controls the Company within the meaning of the Securities Act or the Exchange
Act shall have the same rights to contribution as the Company. The Holders'
respective obligations to contribute pursuant to this Section 5 are several in
proportion to the respective amount of Registrable Securities they have sold
pursuant to a Registration Statement and not joint. The remedies provided for in
this Section 5 are not exclusive and shall not limit any rights or remedies
which may otherwise be available to any indemnified party at law or in equity.

      (e) The indemnity and contribution provisions contained in this Section 5
shall remain operative and in full force and effect regardless of (i) any
termination of this Agreement, (ii) any investigation made by or on behalf of
the Initial Purchaser, any Holder or any person controlling the Initial
Purchaser or Holder, or by or on behalf of the Company, its officers or
directors or any person controlling the Company, and (iii) any sale of
Registrable Securities pursuant to the Shelf Registration Statement.

      6. Holder's Obligations. Each Holder agrees, by acquisition of the
Registrable Securities, that no Holder of Registrable Securities shall be
entitled to sell any of such Registrable Securities pursuant to a Shelf
Registration Statement or to receive a Prospectus relating thereto, unless such
Holder has furnished the Company with a Notice and Questionnaire as required
pursuant to Section 3(a) hereof (including the information required to be
included in such Notice and Questionnaire) and the information set forth in the
next sentence. Each Notice Holder agrees promptly to furnish to the Company all
information required to be disclosed in order to make the information previously
furnished to the Company by such Notice Holder not misleading and any other
information regarding such Notice Holder and the distribution of such
Registrable Securities as the Company may from time to time reasonably request.
Any sale of any Registrable Securities by any Notice Holder shall constitute a
representation and warranty by such Notice Holder that the information relating
to such Notice Holder and its plan of distribution is as set forth in the
Prospectus delivered by such Notice Holder in connection with such disposition,
that such Prospectus does not as of the time of such sale contain any untrue
statement of a material fact relating to or provided by such Notice Holder or
its plan of distribution and that such Prospectus does not as of the time of
such sale omit to state any material fact relating to or provided by such Notice
Holder or its plan of distribution necessary in order to make the statements in
such Prospectus, in the light of the circumstances under which they were made,
not misleading.

      7. Additional Interest.

      (a) Notwithstanding any postponement of the effectiveness pursuant to
Section 2(a) hereof, if (i) on or prior to the 90th day following the Issue
Date, a Shelf Registration Statement has not been filed with the Commission,
(ii) on or prior to the 210th day following the Issue Date, such initial Shelf
Registration Statement is not declared effective by the Commission, (iii) after
the effectiveness date of any Shelf Registration Statement, (x) such Shelf
Registration Statement ceases to be effective or usable for the offer and sale
of Registrable Securities (other than due to a Suspension Period), and the
Company fails to file (and have declared effective), within five Business Days,
a post-effective amendment to such Shelf Registration Statement or

                                       14
<PAGE>
amendment or supplement to the Prospectus contained therein or such other
document with the Commission to make such Shelf Registration Statement effective
or such Prospectus usable, or (y) the Suspension Periods exceed 45 or 60
calendar days, as applicable, whether or not consecutive, in any 90 calendar day
period, or more than 120 calendar days, whether or not consecutive, during any
360 calendar day period during the Effectiveness Period, or (iv) the Company
shall have failed to timely comply with any of its obligations set forth in
Section 3(a)(ii) hereof (each, a "Registration Default"), the Company shall be
required to pay additional interest ("Additional Interest"), from and including
the day following such Registration Default to but excluding the day on which
such Registration Default is cured, at a rate per annum equal to an additional
one-quarter of one percent (0.25%) of the Applicable Amount to and including the
90th day following such Registration Default, and one-half of one percent
(0.50%) thereof from and after the 91st day following such Registration Default.
In the event any Registrable Securities that are Securities are converted into
Common Stock during the continuance of a Registration Default, the Company will
deliver to each Holder converting Securities during the continuance of a
Registration Default 103% of the number of shares of Common Stock the Holder
would have otherwise received upon conversion ("Additional Shares") and no
Additional Interest shall be payable on such converted Securities.

      (b) In the case of a Registration Default described in Sections
7(a)(i)-(iii) above, Additional Interest, if any, shall be payable only to
Notice Holders and, in respect of a Registration Default described in Section
7(a)(iv) above, Additional Interest, if any, shall be payable only to Notice
Holders to whom such Registration Default relates.

      (c) Any amounts to be paid as Additional Interest pursuant to paragraph
(a) of this Section 7 shall be paid in cash semiannually in arrears, with the
first semiannual payment due on the first interest payment date following the
date on which such Additional Interest begins to accrue, to the Notice Holders
in whose name the Securities or Common Stock issued upon conversion of the
Securities are registered at the close of business on June 15 or December 15,
whether or not a Business Day, immediately preceding the relevant interest
payment date.

      (d) Except as provided in Section 8(a) hereof, the Additional Interest or
Additional Shares as set forth in this Section 7 shall be the exclusive cash (or
asset, as the case may be) remedy available to the Holders of Registrable
Securities for such Registration Default. In no event shall the Company be
required to pay Additional Interest in excess of the applicable maximum amount
of one-half of one percent (0.50%) set forth above, regardless of whether one or
multiple Registration Defaults exist.

      8. Miscellaneous.

      (a) Specific Performance. The parties hereto acknowledge that there would
be no adequate remedy at law if the Company fails to perform any of its
obligations hereunder and that the Initial Purchaser and the Holders from time
to time may be irreparably harmed by any such failure, and accordingly agree
that the Initial Purchaser and such Holders, in addition to any other remedy to
which they may be entitled at law or in equity and without limiting the remedies
available to the Notice Holders under Section 7 hereof, shall be entitled to
compel specific performance of the obligations of the Company under this
Registration Rights Agreement in

                                       15
<PAGE>
accordance with the terms and conditions of this Registration Rights Agreement,
in any court of the United States or any State thereof having jurisdiction.

      (b) Amendments and Waivers. This Agreement, including this Section 8(b),
may be amended, and waivers or consents to departures from the provisions hereof
may be given, only by a written instrument duly executed by the Company and a
Majority of Holders. Each Holder of Registrable Securities outstanding at the
time of any such amendment, waiver or consent or thereafter shall be bound by
any amendment, waiver or consent effected pursuant to this Section 8(b), whether
or not any notice, writing or marking indicating such amendment, waiver or
consent appears on the Registrable Securities or is delivered to such Holder.

      (c) Notices. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand delivery, by telecopier, by
courier guaranteeing overnight delivery or by first-class mail, return receipt
requested, and shall be deemed given (i) when made, if made by hand delivery,
(ii) upon confirmation, if made by telecopier, (iii) one (1) Business Day after
being deposited with such courier, if made by overnight courier or (iv) on the
date indicated on the notice of receipt, if made by first-class mail, to the
parties as follows:

      (w)   if to a Holder of Registrable Securities, at the most current
address given by such Holder to the Company in a Notice and Questionnaire or any
amendment thereto;

      (x)   if to the Company, to:

            Concord Communications, Inc.
            600 Nickerson Road
            Marlboro, MA  01752
            Attention:  Chief Financial Officer
            Telephone: (508) 460-4646
            Facsimile:  (508) 481-9772

            with a copy to:

            Testa, Hurwitz & Thibeault, LLP
            125 High Street
            Boston, MA 02110
            Attention:  Kevin M. Barry, Esq.

      (y)   if to the Initial Purchaser, to:

            Bear, Stearns & Co. Inc.
            383 Madison Avenue
            New York, NY  10179
            Attention: Stephen Parish
            Facsimile: (212) 272-3485

or to such other address as such person may have furnished to the other persons
identified in this Section 8(c) in writing in accordance herewith.

                                       16
<PAGE>
      (d) Parties in Interest. The parties to this Agreement intend that all
Holders of Registrable Securities shall be entitled to receive the benefits of
this Agreement and that any Notice Holder shall be bound by the terms and
provisions of this Agreement by reason of such election with respect to the
Registrable Securities which are included in a Shelf Registration Statement. All
the terms and provisions of this Agreement shall be binding upon, shall inure to
the benefit of and shall be enforceable by the respective successors and assigns
of the parties hereto and any Holder from time to time of the Registrable
Securities to the aforesaid extent. In the event that any transferee of any
Holder of Registrable Securities shall acquire Registrable Securities, in any
manner, whether by gift, bequest, purchase, operation of law or otherwise, such
transferee shall, without any further writing or action of any kind, be entitled
to receive the benefits of and, if a Notice Holder, be conclusively deemed to
have agreed to be bound by and to perform all of the terms and provisions of
this Agreement to the aforesaid extent.

      (e) Counterparts. This Agreement may be executed in any number of
counterparts and by the parties hereto in separate counterparts, each of which
when so executed shall be deemed to be an original and all of which taken
together shall constitute one and the same agreement.

      (f) Headings. The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof.

      (g) Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the State of New York.

      (h) Severability. In the event that any one or more of the provisions
contained herein, or the application thereof in any circumstances, is held
invalid, illegal or unenforceable in any respect for any reason, the validity,
legality and enforceability of any such provision in every other respect and of
the remaining provisions hereof shall not be in any way impaired or affected
thereby, it being intended that all of the rights and privileges of the parties
hereto shall be enforceable to the fullest extent permitted by law.

      (i) Survival. The respective indemnities, agreements, representations,
warranties and other provisions set forth in this Agreement or made pursuant
hereto shall remain in full force and effect, regardless of any investigation
(or any statement as to the results thereof) made by or on behalf of any Notice
Holder, any director, officer or partner of such Holder, any agent or
underwriter, any director, officer or partner of such agent or underwriter, or
any controlling person of any of the foregoing, and shall survive the transfer
and registration of the Registrable Securities of such Holder.

      9. Submission to Jurisdiction; Appointment of Agent for Service.

      The Company agrees that any suit, action or proceeding against the Company
arising out of or based upon this Agreement or the transactions contemplated
hereby may be instituted in any state or federal court in The City of New York,
New York, and waives any objection which it may now or hereafter have to the
laying of venue of any such proceeding, and irrevocably submits to the
non-exclusive jurisdiction of such courts in any suit, action or proceeding. The
Company expressly accepts the non-exclusive jurisdiction of any such court in
respect of any

                                       17
<PAGE>
such suit, action or proceeding. The Company agrees that a final judgment in any
such proceeding brought in any such court shall be conclusive and binding
thereupon and may be enforced in any other court in the jurisdiction to which
the Company is or may be subject by suit upon such judgment.

                                       18
<PAGE>
Please confirm that the foregoing correctly sets forth the agreement between the
Company and you.

                                           Very truly yours,

                                           Concord Communications, Inc.

                                           By:  /s/ Melissa H. Cruz
                                                -------------------------------
                                                Name: Melissa H. Cruz
                                                Title: Executive Vice President
                                                       of Business Services,
                                                       Chief Financial Officer
                                                       and Treasurer

Accepted as of the date hereof:
      Bear, Stearns & Co. Inc.

      By:  /s/ Stephen Parish
           -------------------------------------
           Name: Stephen Parish
           Title: Senior Managing Director

                                       19
<PAGE>

                                                                      APPENDIX A

                          CONCORD COMMUNICATIONS, INC.

                  FORM OF NOTICE OF REGISTRATION STATEMENT AND
                SELLING SECURITYHOLDER ELECTION AND QUESTIONNAIRE
                     3.0% CONVERTIBLE SENIOR NOTES DUE 2023

NOTICE

         Concord Communications, Inc. (the "Company") has filed, or intends
shortly to file, with the Securities and Exchange Commission (the "Commission")
a registration statement on Form S-3 or such other Form as may be available (the
"Shelf Registration Statement") for the registration and resale under Rule 415
of the Securities Act of 1933, as amended (the "Securities Act"), of the
Company's Convertible Senior Notes due 2023 (CUSIP No. 206186AA6) (the "Notes"),
and common stock, par value $0.01 per share, issuable upon conversion thereof
(the "Shares" and together with the Notes, the "Transfer Restricted Securities")
in accordance with the terms of the Registration Rights Agreement, dated as of
December 8, 2003 (the "Registration Rights Agreement") between the Company and
Bear, Stearns & Co. Inc. A copy of the Registration Rights Agreement is
available from the Company. All capitalized terms not otherwise defined herein
have the meanings ascribed thereto in the Registration Rights Agreement.

         To sell or otherwise dispose of any Transfer Restricted Securities
pursuant to the Shelf Registration Statement, a beneficial owner of Transfer
Restricted Securities generally will be required to be named as a Selling
Securityholder in the related Prospectus, deliver a Prospectus to purchasers of
Transfer Restricted Securities, be subject to certain civil liability provisions
of the Securities Act and be bound by those provisions of the Registration
Rights Agreement applicable to such beneficial owner (including certain
indemnification rights and obligations, as described below). To be included in
the Shelf Registration Statement, this Election and Questionnaire must be
completed, executed and delivered to the Company at the address set forth herein
for receipt PRIOR TO OR ON THE 20TH CALENDAR DAY FROM THE RECEIPT HEREOF (the
"Election and Questionnaire Deadline"). Beneficial Owners that do not complete
and return this Election and Questionnaire prior to the Election and
Questionnaire Deadline and deliver it to the Company as provided below will not
be named as Selling Securityholders in the Shelf Registration Statement and,
therefore, will not be permitted to sell any Transfer Restricted Securities
pursuant to the Shelf Registration Statement.

         Certain legal consequences arise from being named as a Selling
Securityholder in the Shelf Registration Statement and the related Prospectus.
Accordingly, holders and beneficial owners of Transfer Restricted Securities are
advised to consult their own securities law counsel regarding the consequences
of being named or not being named as a Selling Securityholder in the Shelf
Registration Statement and the related Prospectus.

                                    ELECTION

         The undersigned holder (the "Selling Securityholder") of Transfer
Restricted Securities hereby elects to include in the Shelf Registration
Statement the Transfer Restricted Securities beneficially owned by it and listed
below in Item III (unless otherwise specified under Item III). The undersigned,
by signing and returning this Election and Questionnaire, understands that it
will be bound with respect to such Transfer Restricted Securities by the terms
and conditions of this Election and Questionnaire and the Registration Rights
Agreement.

         Pursuant to the Registration Rights Agreement, the Selling
Securityholder has agreed to indemnify and hold harmless the Company, the
Company's directors, the Company's officers, employees, representatives and
agents and each person, if any, who controls the Company within the meaning of
either Section 15 of the Securities Act or Section 20 of the Exchange Act, from
and against certain losses arising in connection with statements concerning the
Selling Securityholder made in the Shelf Registration Statement or the related
Prospectus in reliance upon the information provided in this Election and
Questionnaire.

         The Selling Securityholder hereby provides the following information to
the Company and represents and warrants that such information is accurate and
complete:

                                  QUESTIONNAIRE

I.      A.  Full Legal Name of Selling Securityholder:
_______________________________________________________________________________

                                      A-1

<PAGE>

        B.  Full legal name of registered holder (if not the same as (a) above)
            through which Transfer Restricted Securities listed in (3) below are
            held:

_______________________________________________________________________________

        C.  Full legal name of DTC participant (if applicable and if not the
            same as (b) above) through which Transfer Restricted Securities
            listed in Item III are held:

_______________________________________________________________________________

II.     Address for notices to Selling Securityholders:

_______________________________________________________________________________

_______________________________________________________________________________

Telephone:       ___________________________

Fax:             ___________________________

Contact Person:  ___________________________

III.    Beneficial ownership of Transfer Restricted Securities:

        A.       Type of Transfer Restricted Securities beneficially owned, and
                 principal amount of Notes or number of shares of Common Stock,
                 as the case may be, beneficially owned:

        _______________________________________________________________________

        B.       CUSIP No(s). of such Transfer Restricted Securities
                 beneficially owned:

        _______________________________________________________________________

        C.       Amount of Transfer Restricted Securities that the undersigned
                 wishes to be included in the Shelf Registration Statement:

        _______________________________________________________________________

IV.     Beneficial ownership of the Company's securities owned by the Selling
        Securityholder:

        EXCEPT AS SET FORTH BELOW IN THIS ITEM IV, THE UNDERSIGNED IS NOT THE
BENEFICIAL OR REGISTERED OWNER OF ANY SECURITIES OF THE COMPANY OTHER THAN THE
TRANSFER RESTRICTED SECURITIES LISTED ABOVE IN ITEM III ("Other Securities").

        A.       Type and amount of Other Securities beneficially owned by the
                 Selling Securityholder:

        _______________________________________________________________________

        B.       CUSIP No(s). of such Other Securities beneficially owned:

        _______________________________________________________________________

V.      Relationship with the Company:

                                      A-2
<PAGE>

         Except as set forth below, neither the undersigned nor any of its
affiliates, officers, directors or principal equity holders (5% or more) has
held any position or office or has had any other material relationship with the
Company (or their predecessors or affiliates) during the past three years.

State any exception here:

_______________________________________________________________________________

VI.      Plan of Distribution:

         Except as set forth below, the undersigned (including its donees or
pledgees) intends to distribute the Transfer Restricted Securities listed above
in Item III pursuant to the Shelf Registration Statement only as follows (if at
all). Such Transfer Restricted Securities may be sold from time to time directly
by the undersigned or, alternatively, through underwriters, broker-dealers or
agents. If the Transfer Restricted Securities are sold through underwriters or
broker-dealers, the Selling Securityholder will be responsible for underwriting
discounts or commissions or agent's commissions. Such Transfer Restricted
Securities may be sold in one or more transactions at fixed prices, at
prevailing market prices at the time of sale, at varying prices determined at
the time of sale, or at negotiated prices. Such sales may be effected in
transactions (which may involve crosses or block transactions):

         1.       on any national securities exchange or quotation service on
                  which the Transfer Restricted Securities may be listed or
                  quoted at the time of sale;

         2.       in the over-the-counter market;

         3.       in transactions otherwise than on such exchanges or services
                  or in the over-the-counter market; or

         4.       through the writing of options.

         In connection with sales of the Transfer Restricted Securities or
otherwise, the undersigned may enter into hedging transactions with
broker-dealers, which may in turn engage in short sales of the Transfer
Restricted Securities and deliver Transfer Restricted Securities to close out
such short positions, or loan or pledge Transfer Restricted Securities to
broker-dealers that in turn may sell such securities. State any exceptions here:

_______________________________________________________________________________

_______________________________________________________________________________

Note: In no event will such method(s) of distribution take the form of an
underwritten offering of the Transfer Restricted Securities without the prior
agreement of the Company.

         By signing below, the Selling Securityholder acknowledges that it
understands its obligation to comply, and agrees it will comply, with the
prospectus delivery requirements and other provisions of the Securities Act and
Exchange Act and the respective rules and regulations promulgated thereunder,
particularly Regulation M thereunder (or any successor rules or regulations), in
connection with any offering of Transfer Restricted Securities pursuant to the
Shelf Registration Statement.

         If the Selling Securityholder transfers all or any portion of the
Transfer Restricted Securities listed in Item III above after the date on which
such information is provided to the Company, the Selling Securityholder agrees
to notify the transferee(s) at the time of the transfer of its rights and
obligations under this Election and Questionnaire and the Registration Rights
Agreement and agrees to deliver a notice of such transfer, in substantially the
form attached as Exhibit 1 to this Election and Questionnaire, to the Trustee
and the Company.

         By signing below, the Selling Securityholder consents to the disclosure
of the information contained herein in its answers to Items I through VI above
and the inclusion of such information in the Shelf Registration Statement and
the related Prospectus. The Selling Securityholder understands that such
information will be relied upon by the Company in connection with the
preparation or amendment of the Shelf Registration Statement and the related
Prospectus.

                                      A-3
<PAGE>

         In accordance with the Selling Securityholder's obligation under the
Registration Rights Agreement to provide such information as may be required by
law for inclusion in the Shelf Registration Statement, the Selling
Securityholder agrees to promptly notify the Company of any inaccuracies or
changes in the information provided herein that may occur subsequent to the date
hereof at any time while the Shelf Registration Statement remains effective. All
notices hereunder and pursuant to the Registration Rights Agreement shall be
made in writing at the address set forth below.

         Once this Election and Questionnaire is executed by the Selling
Securityholders and received by the Company, the terms of this Election and
Questionnaire and the representations and warranties contained herein shall be
binding on, shall inure to the benefit of and shall be enforceable by the
respective successors, heirs, personal representatives and assigns of the
Company and the Selling Securityholder with respect to the Transfer Restricted
Securities beneficially owned by such Selling Securityholder and listed in Item
III above. This Agreement shall be governed by, and construed in accordance
with, the laws of the State of New York without regard to the conflicts-of-laws
provisions thereof.

                                      A-4
<PAGE>

         IN WITNESS WHEREOF, the undersigned, by authority duly given, has
caused this Election and Questionnaire to be executed and delivered either in
person or by its authorized agent.

Dated:

                                           Beneficial Owner

                                           By: _______________________________
                                               Name:
                                               Title:

Please return the completed and executed Election and Questionnaire for receipt
PRIOR TO OR ON THE 20TH CALENDAR DAY FROM RECEIPT HEREOF to:

Concord Communications, Inc. at:

         600 Nickerson Road
         Marlboro, Massachusetts 01752
         Attention: Chief Financial Officer

with a copy to:

         Testa, Hurwitz & Thibeault, LLP
         125 High Street
         Boston, MA  02110
         Attention:  Paul L. Manias, Esq.

                                      A-5
<PAGE>

                                                                      APPENDIX A

                    EXHIBIT 1 TO ELECTION AND QUESTIONNAIRE

                           NOTICE OF TRANSFER PURSUANT
                            TO REGISTRATION STATEMENT

Concord Communications, Inc.
600 Nickerson Road
Marlboro, MA  01752

Re:   Concord Communications, Inc.'s
      Convertible Senior Notes due ________, 2023 (the "Notes")

Dear Sirs:

Please be advised that __________ has transferred $_________ aggregate principal
amount of the above-referenced Notes or ________ shares of the Company's common
stock issued on conversion or repurchase of Notes, pursuant to the Registration
Statement on Form S-3 (File No. 333-________) filed by the Company.

We hereby certify that the prospectus delivery requirements, if any, of the
Securities Act of 1933, as amended, have been satisfied with respect to the
transfer described above and that the above named beneficial owner of the Notes
or common stock is named as a selling securityholder in the Prospectus dated
___________, or in amendments or supplements thereto, and that the aggregate
principal amount of the Notes or number of shares of common stock transferred
are [all or a portion of] the Notes or common stock listed in such Prospectus,
as amended or supplemented, opposite such owner's name.

                                                 Very truly yours,

                                                 [name]

                                                 By:____________________________

                                                         (Authorized Signature)

Dated:__________________<PAGE>

                                                                     EXHIBIT 4.3

                                 AMENDMENT NO. 1
                                     TO THE
                              ARMOR HOLDINGS, INC.
                            2002 STOCK INCENTIVE PLAN

         The following amendment is hereby made to the Armor Holdings, Inc. 2002
Stock Incentive Plan (the "Plan"):

         Section 5.8 of the Plan is hereby amended in its entirety and replaced
by the following new Section 5.8:

                  "5.8 Modification, Extension or Renewal. The Committee may
         modify, extend or renew outstanding Options and authorize the grant of
         new Options in substitution therefor, provided that (i) except as
         expressly provided for in the Plan or an Award Agreement, any such
         action may not, without the written consent of a Participant, impair
         any of such Participant's rights under any Option previously granted
         and (ii) except as provided for in Section 18 of the Plan, Options
         issued hereunder will not be repriced, replaced or regranted through
         cancellation or by lowering the Exercise Price of a previously granted
         Award without prior approval of the Company's Stockholders. Any
         outstanding ISO that is modified, extended, renewed or otherwise
         altered will be treated in accordance with Section 424(h) of the Code."

         The Plan was amended by the Board of Directors of Armor Holdings, Inc.
as of June 18, 2002.

<PAGE>

                                  CERTIFICATION

         The undersigned, being the Secretary of Armor Holdings, Inc., a
Delaware corporation, hereby certifies that the foregoing is a true and complete
copy of Amendment No. 1 to the Armor Holdings, Inc. 2002 Stock Incentive Plan,
as duly adopted by the Board of Directors of the Company on June 18, 2002, and
that said Amendment No. 1 to Armor Holdings, Inc. 2002 Stock Incentive Plan is
in full force and effect on the date hereof, without further amendment or
modification.

                                       /s/ Robert R. Schiller
                                       ----------------------
                                       Robert R. Schiller, Secretary of
                                       Armor Holdings, Inc.

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