Exhibit 99.1

                    CERTIFICATION PURSUANT TO SECTION 906 OF
                         THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of NetScout Systems, Inc. (the
"Company") on Form 10-Q for the quarterly period ended June 30, 2002, as
filed with the Securities and Exchange Commission on the date hereof (the
"Report"), I, Anil K. Singhal, Chief Executive Officer of the Company, hereby
certify pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section
906 of the Sarbanes-Oxley Act of 2002, that: (1) the Report fully complies
with the requirements of Section 13(a) or 15(d) of the Securities Exchange
Act of 1934; and (2) the information contained in the Report fairly presents,
in all material respects, the financial condition and results of operations
of the Company.

/s/Anil K. Singhal

Anil K. Singhal
Chief Executive Officer
August 14, 2002