<PAGE>


                                                                   EXHIBIT 10.24



                          LOAN MODIFICATION AGREEMENT

         This Loan Modification Agreement (this "Loan Modification Agreement")
is entered into as of March 10, 2002, by and between SILICON VALLEY BANK, a
California-chartered bank, with its principal place of business at 3003 Tasman
Drive, Santa Clara, California 95054 and with a loan production office located
at One Newton Executive Park, Suite 200, 2221 Washington Street, Newton,
Massachusetts 02462, doing business under the name "Silicon Valley East"
("Bank") and NETSCOUT SYSTEMS, INC., a Delaware corporation with offices at 310
Littleton Road, Westford, Massachusetts 01886-4105 ("Borrower").

1. DESCRIPTION OF EXISTING INDEBTEDNESS AND OBLIGATIONS. Among other
indebtedness and obligations which may be owing by Borrower to Bank, Borrower is
indebted to Bank pursuant to a certain loan arrangement dated as of March 12,
1998, evidenced by, among other documents, a certain Amended and Restated Loan
and Security Agreement dated as of March 12, 1998 between Borrower and Bank, as
amended by certain Loan Modification Agreements between Borrower and Bank dated
March 11, 1999, March 10, 2000, June 27, 2000, March 9, 2001, August 14, 2001
and September 7, 2001 (as may be amended from time to time, the "Loan
Agreement"). The Loan Agreement established a working capital line of credit in
favor of Borrower in the maximum principal amount of Ten Million Dollars
($10,000,000.00) (the "Committed Revolving Line"). Capitalized terms used but
not otherwise defined herein shall have the same meaning as in the Loan
Agreement.

Hereinafter, all indebtedness and obligations owing by Borrower to Bank shall be
referred to as the "Obligations".

2. DESCRIPTION OF COLLATERAL. Repayment of the Obligations is secured by the
Collateral as described in the Loan Agreement (together with any other
collateral security granted to Bank, the "Security Documents").

Hereinafter, the Security Documents, together with all other documents
evidencing or securing the Obligations shall be referred to as the "Existing
Loan Documents".

3. DESCRIPTION OF CHANGE IN TERMS.

         A. Modifications to Loan Agreement.

                  1.       The Loan Agreement shall be amended by deleting
                           Section 2.1.1(a) and inserting in lieu thereof the
                           following:

                                    "(a) Bank shall make Advances not exceeding
                                    (i) the Committed Revolving Line or the
                                    Borrowing Base, whichever is less, minus
                                    (ii) the amount of all outstanding Letters
                                    of Credit (including drawn but unreimbursed
                                    Letters of Credit), minus (iii) the FX
                                    Reserve, and minus (iv) the aggregate
                                    outstanding Advances hereunder (including
                                    any Cash Management Services). Amounts
                                    borrowed under this Section may be repaid
                                    and reborrowed during the term of this
                                    Agreement."

                  2.       The Loan Agreement shall be amended by deleting
                           Section 2.1.2 entitled "Letters of Credit" and
                           inserting in lieu thereof the following:

                                    "2.1.2 Letters of Credit Sublimit. If there
                                    is availability for Credit Extensions under
                                    Section 2.1.1(a), Bank shall issue or have
                                    issued Letters of Credit for Borrower's
                                    account not exceeding (i) the lesser of the
                                    Committed Revolving Line or the Borrowing
                                    Base, minus (ii) the outstanding principal
                                    balance of any Advances (including any Cash
                                    Management Services), minus (iii) the FX
                                    Reserve, minus (iv) the amount of all
                                    Letters of Credit (including drawn but
                                    unreimbursed Letters of Credit). The face
                                    amount of outstanding Letters of Credit
                                    (including drawn but unreimbursed Letters of
                                    Credit) may not exceed $5,000,000.00. Each
                                    Letter of Credit shall be secured by cash on
                                    terms acceptable to Bank on and after


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                                    (i) the Revolving Maturity Date if the term
                                    of the Committed Revolving Line is not
                                    extended by Bank, or (ii) the occurrence of
                                    an Event of Default hereunder. All Letters
                                    of Credit shall be, in form and substance,
                                    acceptable to Bank in its sole discretion
                                    and shall be subject to the terms and
                                    conditions of Bank's form of standard
                                    Application and Letter of Credit Agreement.
                                    Borrower agrees to execute any further
                                    documentation in connection with the Letters
                                    of Credit as Bank may reasonably request.
                                    The obligation of Borrower to immediately
                                    reimburse Bank for drawings made under
                                    Letters of Credit shall be absolute,
                                    unconditional and irrevocable, and shall be
                                    performed strictly in accordance with the
                                    terms of this Agreement and such Letters of
                                    Credit, under all circumstances whatsoever."

                  3.       The Loan Agreement shall be amended by incorporating
                           the following text as Section 2.1.4 to appear
                           immediately following Section 2.1.3 thereof:

                                    "2.1.4 Foreign Exchange Sublimit. If there
                                    is availability for Credit Extensions under
                                    Section 2.1.1(a), then Borrower may enter
                                    into foreign exchange forward contracts with
                                    the Bank under which Borrower commits to
                                    purchase from or sell to Bank a set amount
                                    of foreign currency more than one business
                                    day after the contract date (the "FX Forward
                                    Contract"). Bank shall subtract 10% of each
                                    outstanding FX Forward Contract from the
                                    foreign exchange sublimit, which sublimit is
                                    a maximum of $1,000,000.00 (the "FX
                                    Reserve"). The total FX Forward Contracts at
                                    any one time may not exceed 10 times the
                                    amount of the FX Reserve. Bank may terminate
                                    the FX Forward Contracts if an Event of
                                    Default occurs."

                  4.       The Loan Agreement shall be amended by deleting
                           Section 2.2 entitled "Overadvances" and inserting in
                           lieu thereof the following:

                                    "Overadvances. If Borrower's Obligations
                                    under Sections 2.1.1, 2.1.2, 2.1.3 and 2.1.4
                                    exceed the lesser of either (i) the
                                    Committed Revolving Line or (ii) the
                                    Borrowing Base, Borrower must immediately
                                    pay in cash to Bank the excess."

                  5.       The Loan Agreement shall be amended by deleting the
                           following text appearing in paragraph (a) of Section
                           6.2 thereof entitled "Financial Statements, Reports,
                           Certificates":

                                    "(iii) (upon Borrower's successful initial
                                    public offering) within 5 days of filing,
                                    copies of all statements, reports and
                                    notices made available to Borrower's
                                    security holders or to any holders of
                                    Subordinated Debt and all reports on Form
                                    10-K, 10-Q and 8-K filed with the Securities
                                    and Exchange Commission;"

                           and inserting in lieu thereof the following:

                                    "(iii) within 5 days of filing, copies of
                                    all statements, reports and notices made
                                    available to Borrower's security holders or
                                    to any holders of Subordinated Debt and all
                                    reports on Form 10-K, 10-Q and 8-K filed
                                    with the Securities and Exchange Commission
                                    (copies of such SEC filings furnished to
                                    Bank shall serve as the Bank's Compliance
                                    Certificate described herein);"

                  6.       The Loan Agreement shall be amended by deleting the
                           following text appearing as Section 6.2(c) thereof
                           entitled "Financial Statements, Reports,
                           Certificates":

                                    "(c) within 45 days of the last day of each
                                    quarter, Borrower will deliver to Bank with
                                    the quarterly financial statements a
                                    Compliance Certificate signed by a
                                    Responsible Officer."


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                  7.       The Loan Agreement shall be amended by deleting
                           Section 6.2(d) and inserting in lieu thereof the
                           following:

                                    "(d) The Bank shall have the right to audit
                                    Borrower's Collateral at Borrower's expense,
                                    but such audit shall be conducted no more
                                    often than once every twelve (12) months and
                                    only when Advances were requested or
                                    outstanding (other than the issuance of
                                    Letters of Credit and Cash Management
                                    Services) during the preceding twelve (12)
                                    month period. Notwithstanding the foregoing,
                                    the Bank may audit Borrower's Collateral at
                                    any time during the continuance of an Event
                                    of Default. Notwithstanding the foregoing,
                                    until the Bank has completed an audit of
                                    Borrower's Collateral, with results
                                    satisfactory to the Bank in its sole
                                    discretion, no new Advances shall be made to
                                    Borrower under the Committed Revolving Line
                                    (other than the issuance of Letters of
                                    Credit and Cash Management Services)."

                  8.       Effective as of the quarter ending December 31, 2001,
                           the Loan Agreement shall be amended by deleting
                           Section 6.7 entitled "Financial Covenants" and
                           inserting in lieu thereof the following:

                                    "6.7 Financial Covenants.

                                    (a) Adjusted Quick Ratio. Borrower shall
                                    maintain, as of the last day of each
                                    quarter, a ratio of Quick Assets to Current
                                    Liabilities minus Deferred Maintenance
                                    Revenue of at least 1.50 to 1.0. For
                                    purposes hereof, "Deferred Maintenance
                                    Revenue" is all amounts received in advance
                                    of performance under maintenance contracts
                                    and not yet recognized as revenue.

                                    (b) EBITDA. Borrower shall maintain, as of
                                    the last day of each quarter: (i) a negative
                                    EBITDA not greater than Two Hundred Thousand
                                    Dollars ($200,000.00) as of the quarter
                                    ending December 31, 2001, and (ii) a
                                    positive EBITDA not less than One Dollar
                                    ($1.00) as of the quarter ending March 31,
                                    2002 and as of the last day of each quarter
                                    thereafter. For purposes hereof, "EBITDA"
                                    shall mean earnings before interest, taxes,
                                    depreciation and amortization in accordance
                                    with GAAP."

                  9.       The Loan Agreement shall be amended by deleting the
                           definition of "Revolving Maturity Date" appearing in
                           Section 13.1 and inserting in lieu thereof the
                           following:

                                    ""Revolving Maturity Date" is March 8,
                                    2003."

                  10.      The Compliance Certificate appearing as Exhibit C to
                           the Loan Agreement is hereby replaced with the
                           Compliance Certificate attached hereto as Exhibit C.

4. FEES. Borrower shall pay to Bank a modification fee for this Amendment in an
amount equal to Twenty-Five Thousand Dollars ($25,000.00), which fee shall be
due on the date hereof and shall be deemed fully earned as of the date hereof.
The Borrower shall also reimburse Bank for all legal fees and expenses incurred
in connection with this amendment to the Existing Loan Documents.

5. ADDITIONAL COVENANTS: RATIFICATION OF PERFECTION CERTIFICATE. Borrower shall
not, without providing the Bank with thirty (30) days prior written notice: (i)
relocate its principal executive office or keep any Collateral in any additional
locations, or (ii) change its jurisdiction of organization, or (iii) change its
organizational structure or type, (iv) change its legal name, or (v) change any
organizational number (if any) assigned by its jurisdiction of organization.


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6. AUTHORIZATION TO FILE. Borrower hereby authorizes Bank to file financing
statements without notice to Borrower, with all appropriate jurisdictions, as
Bank deems appropriate, in order to further perfect or protect Bank's interest
in the Collateral.

7. CONSISTENT CHANGES. The Existing Loan Documents are hereby amended wherever
necessary to reflect the changes described above.

8. RATIFICATION OF LOAN DOCUMENTS. Borrower hereby ratifies, confirms, and
reaffirms all terms and conditions of all security or other collateral granted
to the Bank, and confirms that the indebtedness secured thereby includes,
without limitation, the Obligations.

9. NO DEFENSES OF BORROWER. Borrower agrees that, as of this date, it has no
defenses against the obligations to pay any amounts under the Obligations.

10. CONTINUING VALIDITY. Borrower understands and agrees that in modifying the
existing Obligations, Bank is relying upon Borrower's representations,
warranties, and agreements, as set forth in the Existing Loan Documents. Except
as expressly modified pursuant to this Loan Modification Agreement, the terms of
the Existing Loan Documents remain unchanged and in full force and effect.
Bank's agreement to modifications to the existing Obligations pursuant to this
Loan Modification Agreement in no way shall obligate Bank to make any future
modifications to the Obligations. Nothing in this Loan Modification Agreement
shall constitute a satisfaction of the Obligations. It is the intention of Bank
and Borrower to retain as liable parties all makers of Existing Loan Documents,
unless the party is expressly released by Bank in writing. No maker will be
released by virtue of this Loan Modification Agreement.

11. RIGHT OF SET-OFF. In consideration of Bank's agreement to enter into this
Loan Modification Agreement, Borrower and any guarantor hereby reaffirm and
hereby grant to Bank, a lien, security interest and right of setoff as security
for all Obligations to Bank, whether now existing or hereafter arising upon and
against all deposits, credits, collateral and property, now or hereafter in the
possession, custody, safekeeping or control of Bank or any entity under the
control of Silicon Valley Bank or in transit to any of them. At any time after
the occurrence and during the continuance of an Event of Default, without demand
or notice, Bank may set off the same or any part thereof and apply the same to
any liability or obligation of Borrower and any guarantor even though unmatured
and regardless of the adequacy of any other collateral securing the Obligations.
ANY AND ALL RIGHTS TO REQUIRE BANK TO EXERCISE ITS RIGHTS OR REMEDIES WITH
RESPECT TO ANY OTHER COLLATERAL WHICH SECURES THE OBLIGATIONS, PRIOR TO
EXERCISING ITS RIGHT OF SETOFF WITH RESPECT TO SUCH DEPOSITS, CREDITS OR OTHER
PROPERTY OF THE BORROWER OR ANY GUARANTOR, ARE HEREBY KNOWINGLY, VOLUNTARILY AND
IRREVOCABLY WAIVED.

12. JURISDICTION/VENUE. Borrower accepts for itself and in connection with its
properties, unconditionally, the exclusive jurisdiction of any state or federal
court of competent jurisdiction in the Commonwealth of Massachusetts in any
action, suit, or proceeding of any kind against it which arises out of or by
reason of this Loan Modification Agreement; provided, however, that if for any
reason Bank cannot avail itself of the Courts of The Commonwealth of
Massachusetts, then venue shall lie in Santa Clara County, California.
NOTWITHSTANDING THE FOREGOING, THE BANK SHALL HAVE THE RIGHT TO BRING ANY ACTION
OR PROCEEDING AGAINST THE BORROWER OR ITS PROPERTY IN THE COURTS OF ANY OTHER
JURISDICTION WHICH THE BANK DEEMS NECESSARY OR APPROPRIATE IN ORDER TO REALIZE
ON THE COLLATERAL OR TO OTHERWISE ENFORCE THE BANK'S RIGHTS AGAINST THE BORROWER
OR ITS PROPERTY.

13. COUNTERSIGNATURE. This Loan Modification Agreement shall become effective
only when it shall have been executed by Borrower and Bank (provided, however,
in no event shall this Loan Modification Agreement become effective until signed
by an officer of Bank in California).



            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]


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         This Loan Modification Agreement is executed as a sealed instrument
under the laws of the Commonwealth of Massachusetts as of the date first written
above.

BORROWER:                                BANK:

NETSCOUT SYSTEMS, INC.                   SILICON VALLEY BANK, doing business as
                                         SILICON VALLEY EAST



By: /s/ Lisa Florentino                  By:
    --------------------------------         ----------------------------------
Name: Lisa Florentino                    Name:
      ------------------------------           --------------------------------
Title: V.P. of Finance and               Title:
       Administration                           -------------------------------
       and Chief Accounting Officer


                                         SILICON VALLEY BANK

                                         By: /s/ Maggie Garcia
                                            -----------------------------------

                                         Name: Maggie Garcia
                                               --------------------------------

                                         Title: Administrative Vice President
                                                -------------------------------
                                               (signed in Santa Clara County,
                                                California)


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<PAGE>


                                   EXHIBIT C
                             COMPLIANCE CERTIFICATE


TO: SILICON VALLEY BANK

FROM: NETSCOUT SYSTEMS, INC.

         The undersigned authorized officer of NETSCOUT SYSTEMS, INC. certifies
that under the terms and conditions of the Loan and Security Agreement between
Borrower and Bank (the "Agreement"), (i) Borrower is in complete compliance for
the period ending _______________ with all required covenants except as noted
below and (ii) all representations and warranties of the Borrower in the
Agreement are true and correct in all material respects on this date. Attached
are the required documents supporting the certification. The Officer certifies
that these are prepared in accordance with Generally Accepted Accounting
Principles (GAAP) consistently applied from one period to the next except as
explained in an accompanying letter or footnotes. The Officer acknowledges that
no borrowings may be requested by the Borrower at any time or date of
determination that Borrower is not in compliance with any of the terms of the
Agreement, and that compliance is determined not just at the date this
certificate is delivered.

         PLEASE INDICATE COMPLIANCE STATUS BY CIRCLING YES/NO UNDER "COMPLIES"
COLUMN.

<TABLE>
<CAPTION>

REPORTING COVENANT                                   REQUIRED                                     COMPLIES
------------------                                   --------                                     --------
<S>                                                <C>                                           <C>

Financial statements                               Quarterly within 45 days                        Yes  No

Annual (CPA Audited)                               FYE within 120 days                             Yes  No

BBC and A/R Agings                                 Monthly w/in 30 days when borrowing             Yes  No

                                                   Quarterly w/in 45 days when not borrowing       Yes  No

Form 10-K, 10-Q and 8-K                            Within 5 days of filing                         Yes  No
</TABLE>

<TABLE>
<CAPTION>

FINANCIAL COVENANT                                  REQUIRED                    ACTUAL           COMPLIES
------------------                                  --------                    ------           --------
<S>                                               <C>                         <C>               <C>

Maintain:

Minimum Adjusted Quick Ratio (quarterly)            1.5:1.0                     _______:1.0       Yes  No

Negative EBITDA (quarterly)                         Not greater than $200,000   $__________       Yes  No
                                                    for QE 12/31/01

Positive EBITDA (quarterly)                         Not less than $1.00         $__________       Yes  No
                                                    for QE 3/31/02 and thereafter
</TABLE>



COMMENTS REGARDING EXCEPTIONS: See Attached, if any.

Sincerely,

----------------------------------
SIGNATURE

----------------------------------
TITLE

----------------------------------
DATE


----------------------------------

            BANK USE ONLY

Received by: _____________________
              AUTHORIZED SIGNER

Date: ____________________________


Verified: ________________________
              AUTHORIZED SIGNER

Date: ____________________________

----------------------------------


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