Document:

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                                                                    Exhibit 10.1

                                  LEXENT INC.
                              AND ITS SUBSIDIARIES
                              AMENDED AND RESTATED
                STOCK OPTION AND RESTRICTED STOCK PURCHASE PLAN

         Section 1. Purpose. The purpose of Lexent Inc. and its Subsidiaries
Stock Option and Restricted Stock Purchase Plan, as amended from time to time
(the "Plan"), is to promote the interests of Lexent Inc., a Delaware corporation
(the "Company"), and any Subsidiary thereof and the interests of the Company's
stockholders by providing an opportunity to selected employees and other persons
providing services for the Company or any Subsidiary thereof, including, without
limitation, officers and directors, as of the date of the adoption of the Plan
or at any time thereafter to purchase Common Stock of the Company. By
encouraging such stock ownership, the Company seeks to attract, retain and
motivate such employees and other persons and to encourage such employees and
other persons to devote their best efforts to the business and financial success
of the Company. It is intended that this purpose will be effected by the
granting of "non-qualified stock options" and/or "incentive stock options" to
acquire the Common Stock of the Company and/or by the granting of rights to
purchase the Common Stock of the Company on a "restricted stock" basis. Under
the Plan, except for automatic grants to Outside Directors, the Committee shall
have the authority (in its sole discretion) to grant "incentive stock options"
within the meaning of Section 422(b) of the Code, "non-qualified stock options"
as described in Treasury Regulation Section 1.83-7 or any successor regulation
thereto, or "restricted stock" awards.

         No grant of "incentive stock options" shall be made under this Plan
unless such Plan is approved by the stockholders of the Company within 12 months
of the date of the adoption of such Plan.

         Section 2. Definitions. For purposes of the Plan, the following terms
used herein shall have the following meanings, unless a different meaning is
clearly required by the context:

         2.1. "Award shall mean an award of the right to purchase Common Stock
granted under the provisions of Section 7 of the Plan.

         2.2. "Board of Directors" shall mean the Board of Directors of the
Company.

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         2.3. "Change in Control" shall mean (i) a merger or consolidation in
which the Company is not the surviving corporation (other than a merger or
consolidation with a wholly-owned subsidiary, a reincorporation of the Company
in a different jurisdiction, or other transaction in which there is no
substantial change in the stockholders of the Company or their relative stock
holdings and the Awards and/or Options are assumed, converted or rep1aced by the
successor corporation), (ii) a merger in which the Company is the surviving
corporation but after which the stockholders of the Company immediately prior to
such merger (other than any stockholder that merges, or which owns or controls
another corporation that merges, with the Company in such merger) cease to own
their shares or other equity interest in the Company, (iii) the sale of all or
substantially all of the assets of the Company, or (iv) the acquisition, sale or
transfer of more than 50% of the outstanding shares of the Company by tender
offer or similar transaction.

         2.4. "Code" shall mean the Internal Revenue Code of 1986, as amended.

         2.5. "Committee" shall mean the committee or committees of the Board of
Directors referred to in Section 5 hereof; provided, that if no such committee
or committees are appointed by the Board of Directors, the Board of Directors
shall have all of the authority and obligations of the Committee under the Plan.

         2.6. "Common Stock" shall mean the Common Stock, $.001 par value, of
the Company.

         2.7. "Director Option" shall mean a Non-Qualified Option granted to an
Outside Director pursuant to an Initial Grant or a Suceeding Grant.

         2.8. "Employee" shall mean (i) with respect to an ISO, any person,
including, without limitation, an officer of the Company, who, at the time an
ISO is granted to such person hereunder, is employed by the Company or any
Parent or Subsidiary of the Company, and (ii) with respect to a Non-Qualified
Option and/or an Award, any person employed by, or performing services for, the
Company or any Parent or Subsidiary of the Company, including, without
limitation, officers, directors and Outside Directors.

         2.9. "ISO" shall mean an Option granted to a Participant pursuant to
the Plan that constitutes and shall be treated as an "incentive stock option" as
defined in Section 422(b) of the Code.

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         2.10. "Non-Qualified Option" shall mean an Option granted to a
Participant pursuant to the Plan that is intended to be, and qualifies as, a
"non-qualified stock option" as described in Treasury Regulation Section 1.83-7
or any successor regulation thereto and that shall not constitute or be treated
as an ISO.

         2.11. "Option" shall mean any ISO or Non-Qualified Option granted to an
Employee pursuant to the Plan.

         2.12. "Outside Director" shall mean a member of the Board of Directors
who is not an employee of the Company or any Parent, Subsidiary or affiliate of
the Company.

         2.13. "Participant" shall mean any Employee to whom an Award and/or an
Option is granted under the Plan.

         2.14. "Parent" of the Company shall have the meaning set forth in
Section 424(e) of the Code.

         2.15. "Subsidiary" of the Company shall have the meaning set forth in
Section 424(f) of the Code.

         Section 3. "Eligibility". Awards and/or Options may be granted to any
Employee. Except for automatic grants to Outside Directors pursuant to Section
6.3 hereof, the Committee shall have the sole authority to select the persons to
whom Awards and/or Options are to be granted hereunder, and to determine whether
a person is to be granted a Non-Qualified Option, an ISO or an Award or any
combination thereof. Outside Directors shall only be eligible to receive grants
of Non-Qualified Options pursuant to Section 6.3 hereof. No person shall have
any right to participate in the Plan. Any person selected by the Committee for
participation during any one period will not by virtue of such participation
have the right to be selected as a Participant for any other period. The maximum
number of shares of Common stock which may be the subject of Options and/or
Awards granted to one Employee under the Plan during any calendar year shall be
Two Million (2,000,000) shares.

         Section 4. Common Stock Subject to the Plan.

         4.1. Number of Shares. The total number of shares of Common Stock for
which Options and/or Awards may be granted, under the Plan shall not exceed in
the aggregate Five Million Eight Hundred Thousand (5,800,000) shares of Common
Stock (subject to adjustment as provided in Section 8 hereof).

         4.2. Reissuance. The shares of Common Stock that may be subject to
Options and/or Awards granted under the Plan may be either authorized and
unissued shares or shares reacquired at any time and now or hereafter held as
treasury stock as the Committee

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may determine. In the event that any outstanding Option expires or is
terminated for any reason, the shares allocable to the unexercised portion of
such Option may again be subject to an Option and/or Award granted under the
Plan. If any shares of Common Stock issued or sold pursuant to an Award or the
exercise of an Option shall have been repurchased by the Company, then such
shares may again be subject to an Option and/or Award granted under the Plan.

        4.3     Special ISO Limitations.

        (a)     The aggregate fair market value (determined as of the date an
ISO is granted) of the shares of Common Stock with respect to which ISOs are
exercisable for the first time by an Employee during any calendar year (under
all incentive stock option plans of the Company or any Parent or Subsidiary of
the Company) shall not exceed $100,000.

        (b)     No ISO shall be granted to an Employee who, at the time the ISO
is granted, owns (actually or constructively under the provisions of Section
424(d) of the Code) stock possessing more than 10% of the total combined voting
power of all classes of stock of the Company or any Parent or Subsidiary of the
Company, unless (i) the option price is at least 110% of the fair market value
(determined as of the time the ISO is granted) of the shares of Common Stock
subject to the ISO and (ii) the ISO by its terms is not exercisable more than
five years from the date it is granted.

        4.4     Limitations Not Applicable to Non-Qualified Options or Awards.
Notwithstanding any other provision of the Plan, the provisions of Sections 4.3
(a) and (b) shall not apply, nor shall be construed to apply, to any
Non-Qualified Option or Award granted under the Plan.

        Section 5. Administration of the Plan.

        5.1.    Administration. Subject to the proviso in Section 2.5 hereof,
the Plan may be administered by one or more committees of the Board of
Directors each consisting of no less than two persons (collectively, the
"Committee"). To the extent that the Board of Directors determines it desirable
to qualify transactions hereunder as exempt under the Rule 16b-3 of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), each member
of the Committee administering the Plan as to such transactions shall be a
"Non-Employee Director" within the meaning of Rule 16b-3 promulgated under the
Exchange Act. To the extent that the Board of Directors determines it desirable
to qualify Options granted hereunder as "performance-based compensation" within
the meaning of Section 162(m) of the Code,

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each member of the Committee administering the Plan as to such Options shall be
an "outside director" within the meaning of Treasury regulation Section
1.162-27(e)(3). The Committee shall be appointed from time to time by, and
shall serve at the pleasure of, the Board of Directors.

        5.2.    Grant of Options/Awards.

        (a)     Options. Except for automatic grants to Outside Directors
pursuant to Section 6.3 hereof, the Committee shall have the sole authority and
discretion under the Plan (i) to select the Employees who are to be granted
Options hereunder; (ii) to designate whether any Option to be granted
hereunder is to be an ISO or a Non-Qualified Option; (iii) to establish the
number of shares of Common Stock that may be subject to each Option; (iv) to
determine the time and the conditions subject to which Options may be
exercised in whole or in part; (v) to determine the amount (not less than the
par value per share) and the form of the consideration that may be used to
purchase shares of Common Stock upon exercise of any Option (including, without
limitation, the circumstances under which issued and outstanding shares of
Common Stock owned by a Participant may be used by the Participant to exercise
an Option); (vi) to impose restrictions and/or conditions with respect to
shares of Common Stock acquired upon exercise of an Option; (vii) to determine
the circumstances under which shares of Common Stock acquired upon exercise of
any Option may be subject to repurchase by the Company; (viii) to determine the
circumstances and conditions subject to which shares acquired upon exercise of
an Option may be sold or otherwise transferred, including, without limitation,
the circumstances and conditions subject to which a proposed sale of shares of
Common Stock acquired upon exercise of an Option may be subject to the
Company's right of first refusal (as will as the terms and conditions of any
such right of first refusal); (ix) to establish a vesting provision for any
Option relating to the time when (or the circumstances under which) the Option
may be exercised by a Participant, including, without limitation, vesting
provisions that may be contingent upon (A) the Company's meeting specified
financial goals, (B) a change of control of the Company or (C) the occurrence
of other specified events; (x) to accelerate the time when outstanding Options
may be exercised, provided, however, that any ISOs shall be deemed "accelerated"
within the meaning of Section 424(h) of the Code; and (xi) to establish any
other terms, restrictions and/or conditions applicable to any Option not
inconsistent with the provisions of the Plan.

        (b)     Awards. The Committee shall have the sole authority and
discretion under the Plan (i) to select the Employees who are to be granted
Awards hereunder; (ii) to determine the amount to be paid by a Participant to
acquire shares of Common Stock

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pursuant to an Award, which amount may be equal to, more than, or less than
100% of the fair market value of such shares on the date the Award is granted
(but in no event less than the par value of such shares); (iii) to determine
the time or times and the conditions subject to which Awards may be made; (iv)
to determine the time or times and the conditions subject to which the shares
of Common Stock subject to an Award are to become vested and no longer subject
to repurchase by the Company; (v) to establish transfer restrictions and the
terms and conditions on which any such transfer restrictions with respect to
shares of Common Stock subject to an Award, including, without limitation,
vesting provisions which may be contingent upon (A) the Company's meeting
specified financial goals, (B) a change of control of the Company or (C) the
occurrence of other specified events; (vii) to determine the circumstances
under which shares of Common Stock acquired pursuant to an Award maybe subject
to repurchase by the Company; (viii) to determine the circumstances and
conditions subject to which any shares of Common Stock acquired pursuant to an
Award may be sold or otherwise transferred, including, without limitation, the
circumstances and conditions subject to which a proposed sale of shares of
Common Stock acquired pursuant to an Award may be subject to the Company's right
of first refusal (as well as the terms and conditions of any such right of first
refusal); (ix) to determine the form of consideration that may be used to
purchase shares of Common Stock pursuant to an Award (including, without
limitation, the circumstances under which issued and outstanding shares of
Common Stock owned by a Participant may be used by the Participant to purchase
the Common Stock subject to an Award); (x) to accelerate the time at which any
or all restrictions imposed with respect to any shares of Common Stock subject
to an Award will lapse; and (xi) to establish any other terms, restrictions
and/or conditions applicable to any Award not inconsistent with the provisions
of the Plan.

        5.3     Interpretation. The Committee shall be authorized to interpret
the Plan and may, from time to time, adopt such rules and regulations, not
inconsistent with the provisions of the Plan, as it may deem advisable to carry
out the purposes of the Plan.

        5.4.    Finality. The interpretation and construction by the Committee
of any provision of the Plan, any Option and/or Award granted hereunder or any
agreement evidencing any such Option and/or Award shall be final and conclusive
upon all parties.

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          5.5. Expenses, Etc. All expenses and liabilities incurred by the
Committee in the administration of the Plan shall be borne by the Company. The
Committee may employ attorneys, consultants, accountants or other persons in
connection with the administration of the Plan. The Company, and its officers
and directors, shall be entitled to rely upon the advice, opinions or valuations
of any such persons. No member of the Committee shall be liable for any action,
determination or interpretation taken or made in good faith with respect to the
Plan or any Option and/or Award granted hereunder.

          Section 6. Terms and Conditions of Options.

          6.1. ISOs. The terms and conditions of each ISO granted under the Plan
shall be specified by the Committee and shall be set forth in an ISO agreement
between the Company and the Participant in such form as the Committee shall
approve. The terms and conditions of each ISO shall be such that each ISO issued
hereunder shall constitute and shall be treated as an "incentive stock option"
as defined in Section 422(b) of the Code. The terms and conditions of any ISO
granted hereunder need not be identical to those of any other ISO granted
hereunder.

          The terms and conditions of each ISO shall include the following:

          (a) The option price shall be fixed by the Committee but shall in no
event be less than 100% (or 110% in the case of an Employee referred to in
Section 4.3(b) hereof) of the fair market value of the shares of Common Stock
subject to the ISO on the date the ISO is granted. For purposes of the Plan, the
fair market value per share of Common Stock as of any day shall mean the average
of the closing prices of sales of shares of Common Stock on all national
securities exchanges on which the Common Stock may at the time be listed or, if
there shall have been no sales on any such day, the average of the highest bid
and lowest asked prices on all such exchanges at the end of such day, or, if on
any day the Common Stock shall not be so listed, the average of the
representative bid and asked prices quoted in the NASDAQ system as of 3:30 p.m.,
New York time, on such day, or, if on any day the Common Stock shall not be
quoted in the NASDAQ system, the average of the high and low bid and asked
prices on such day in the over-the-counter market as reported by National
Quotation Bureau Incorporated, or any similar successor organization. If at any
time the Common Stock is not listed on any national securities exchange or
quoted in the NASDAQ system or the over-the-counter market, the fair market
value of the shares of Common Stock subject to an Option on the date the ISO is
granted shall be the fair market value thereof determined in good faith by the
Board of Directors.

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          (b) ISOs, by their terms, shall not be transferable otherwise than by
will or the laws of descent and distribution, and, during a Participant's
lifetime, an ISO shall be exercisable only by the Participant.

          (c) The Committee shall fix the term of all ISOs granted pursuant to
the Plan (including, without limitation, the date on which such ISO shall expire
and terminate); provided, however, that such term shall in no event exceed ten
years from the date on which such ISO is granted (or, in the case of an ISO
granted to an Employee referred to in Section 4.3(b) hereof, such term shall in
no event exceed five years from the date on which such ISO is granted). Each ISO
shall be exercisable in such amount or amounts, under such conditions and at
such times or intervals or in such installments as shall be determined by the
Committee in its sole discretion.

          (d) To the extent that the Company or any Parent or Subsidiary of the
Company is required to withhold any Federal, state or local taxes in respect of
any compensation income realized by any Participant as a result of any
"disqualifying disposition" of any shares of Common Stock acquired upon exercise
of an ISO granted hereunder, the Company shall deduct from any payments of any
kind otherwise due to such Participant the aggregate amount of such Federal,
state or local taxes required to be so withheld or, if such payments are
insufficient to satisfy such Federal, state or local taxes, such Participant
will be required to pay to the Company, or make1 other arrangements satisfactory
to the Company regarding payment to the Company of, the aggregate amount of any
such taxes. All matters with respect to the total amount of taxes to be withheld
in respect of any such compensation income shall be determined by the Board of
Directors, in its sole discretion.

          (e) The terms and conditions of each ISO may include the following
provisions:

          (i) In the event a Participant's employment on a full-time basis by
     the Company or any Parent or Subsidiary of the Company shall be terminated
     for cause or shall be terminated by the Participant for any reason
     whatsoever other than as a result of the Participant's death or
     "disability" (within the meaning of Section 22(e)(3) of the Code), the
     unexercised portion of any ISO held by such Participant at that time may
     only be exercised within 15 days after the date on which the Participant
     ceased to be so employed, and only to the extent that the Participant could
     have otherwise exercised such ISO as of the date on which he ceased to be
     so employed.

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          (ii) In the event a Participant's employment on a full-time basis by
     the Company or any Parent or Subsidiary of the Company shall terminate for
     any reason other than (x) a termination specified in clause (i) above or
     (y) by reason of the Participant's death or "disability" (within the
     meaning of Section 22 (e)(3) of the Code), the unexercised portion of any
     ISO held by such Participant at that time may only be exercised within 30
     days after the date on which the Participant ceased to be so employed, and
     only to the extent that the Participant could have other wise exercised
     such ISO as of the date on which he ceased to be so employed.

          (iii) In the event a Participant shall cease to be employed by the
     Company or any Parent or subsidiary of the Company on a full-time basis by
     reason of his "disability" (within the meaning of Section 22(e)(3) of the
     Code), the unexercised portion of any ISO held by such Participant at that
     time may only be exercised within 180 days after the date on which the
     Participant ceased to be so employed, and only to the extent that the
     Participant could have otherwise exercised such ISO as of the date on which
     he ceased to be so employed.

          (iv) In the event a Participant shall die while in the employ of the
     Company or a Parent or Subsidiary of the Company (or within a period of 15
     day after ceasing to be an Employee for any reason other than his
     "disability" (within the meaning of Section 22(e)(4) of the Code) or
     within a period of 180 days after ceasing to be an Employee by reason of
     such "disability"), the unexercised portion of any ISO held by such
     Participant at the time of his death may only be exercised within 180 days
     after the date of such Participant's death, and only to the extent that the
     Participant could have otherwise exercised such ISO at the time of his
     death. In such event, such ISO may be exercised by the executor or
     administrator of the Participant's estate or by any person or persons who
     shall have acquired the ISO directly from the Participant by bequest or
     inheritance.

          6.2. Non-Qualified Options. The terms and conditions of each
Non-Qualified Option granted under the Plan shall be specified by the Committee,
in its sole discretion, and shall be set forth in a written option agreement
between the Company and the Participant in such form as the Committee shall
approve. The terms and conditions of each Non-Qualified Option will be such (and
each Non-Qualified Option agreement shall expressly so state) that each
Non-Qualified Option issued hereunder shall not constitute nor be treated as an
"incentive stock option" as defined in Section 422(b) of the Code, but will be a
"non-qualified stock option" for Federal, state and local income tax purposes.
The terms and conditions of any Non-Qualified Option

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granted hereunder need not be identical to those of any other Non-Qualified
Option granted hereunder.

          The terms and conditions of each Non-Qualified Option Agreement shall
include the following:

          (a) The option (exercise) price shall be fixed by the Committee and
may be equal to, more than or less than 100% of the fair market value of the
shares of Common Stock subject to the Non-Qualified Option on the date such
Non-Qualified Option is granted as determined in good faith by the Committee.

          (b) The Committee shall fix the term of all Non-Qualified Options
granted pursuant to the Plan (including, without limitation, the date on which
such Non Qualified Option shall expire and terminate). Such term may be more
than ten years from the date on which such Non-Qualified Option is granted. Each
Non-Qualified Option shall be exercisable in such amount or amounts, under such
conditions (including, without limitation, provisions governing the rights to
exercise such Non-Qualified Option), and at such times or interva1s or in such
installments as shall be determined by the Committee in its sole discretion;
provided, however, that in no event shall any Non-Qualified Option granted to
any director or officer of the Company who is subject to Section 16 of the
Exchange Act become exercisable, in whole or in part, prior to the date that is
six months after the date such Non-Qualified Option is granted to such director
or officer.

          (c) Non-Qualified Options shall not be transferable otherwise than by
will or the laws of descent and distribution, and during a Participant's
lifetime a Non-Qualified Option shall be exercisable only by the Participant.

          (d) The terms and conditions of each Non-Qualified Option may include
the following provisions:

          (i) In the event a Participant's employment on a full-time basis by
     the Company or any Parent or Subsidiary of the Company shall be terminated
     for cause or shall be terminated by the Participant for any reason
     whatsoever other than as a result of the Participant's death or
     "disability" (within the meaning of Section 22(e)(3) of the Code), the
     unexercised portion of any Non-Qualified Option held by such Participant at
     that time may only be exercised within 15 days after the date on which the
     Participant ceased to be an Employee, and only to the extent that the
     Participant could have otherwise exercised such Non-Qualified Option as of
     the date on which he ceased to be an Employee.

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          (ii) In the event a Participant's employment on a full-time basis by
     the Company or any Parent or Subsidiary of the Company shall terminate for
     any reason other than (x) a termination specified in clause (i) above or
     (y) by reason of the Participant's death or "disability" (within the
     meaning of Section 22(e)(3) of the Code), the unexercised portion of any
     Non-Qualified Option held by such Participant at that time may only be
     exercised within 30 days after the date on which the Participant ceased to
     be an Employee, and only to the extent that the Participant could have
     otherwise exercised such Non-Qualified Option as of the date on which he
     ceased to be an Employee.

          (iii) In the event a Participant shall cease to be an Employee of the
     Company or any Parent or Subsidiary of the Company on a full-time basis by
     reason of his "disability" (within the meaning of Section 22(e)(3) of the
     Code), the unexercised portion of any Non-Qualified Option held by such
     Participant at that time may only be exercised within 180 days after the
     date on which the Participant ceased to be an Employee, and only to the
     extent that the Participant could have otherwise exercised such
     Non-Qualified Option as of the date on which he ceased to be an Employee.

          (iv) In the event a Participant shall die while an Employee of the
     Company or a Parent or Subsidiary of the Company (or within a period of 15
     days after ceasing to be an Employee for any reason other than his
     "disability" (within the meaning of Section 22(e)(3) of the Code) or within
     a period of 180 days after ceasing to be an Employee by reason of such
     "disability"), the unexercised portion of any Non-Qualified Option held by
     such Participant at the time of his death may only be exercised within 180
     days after the date of such Participant's death, and only to the extent
     that the Participant could have otherwise exercised such Non-Qualified
     Option at the time of his death. In such event, such Non-Qualified Option
     may be exercised by the executor or administrator of the Participant's
     estate or by any person or persons who shall have acquired the
     Non-Qualified Option directly from the Participant by bequest or
     inheritance.

          (e) To the extent that the Company is required to withhold any
Federal, state or local taxes in respect of any compensation income realized by
any Participant in respect of a Non-Qualified Option granted hereunder or in
respect of any shares of Common Stock acquired upon exercise of a Non-Qualified
Option, the Company shall deduct from any payments of any kind otherwise due to
such Participant the aggregate amount of such Federal, state or local taxes
required to be so withheld or, if such payments are insufficient to satisfy such
Federal, state or

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local taxes, or if no such payments are due or to become due to such
Participant, then, such Participant will be required to pay to the Company, or
make other arrangements satisfactory to the Company regarding payment to the
Company of, the aggregate amount of any such taxes. All matters with respect to
the total amount of taxes to be withheld in respect of any such compensation
income shall be determined by the Committee, in its sole discretion.

          6.3 Grants to Outside Directors.

          (a) Each Outside Director who first becomes a member of the Board of
Directors on or after February 17, 2000 (the "Automatic Grant Effective Date")
will be granted a Non-Qualified Option to purchase such number of shares of
Common Stock ("Initial Grant") as the Committee shall determine on the next
business day following the date such Outside Director first becomes a member of
the Board of Directors, unless such Outside Director received Options prior to
the Automatic Grant Effective Date. Each Outside Director who became a member of
the Board of Directors prior to the Automatic Grant Effective Date and who did
not receive a prior grant of Options will receive an Initial Grant on the next
business day following the Automatic Grant Effective Date.

          (b) Immediately following each annual meeting of stockholders, each
Outside Director will be granted a Non-Qualified Option to purchase such number
of shares of Common Stock ("Succeeding Grant") as the Committee shall determine
provided, however, that the Outside Director is a member of the Board of
Directors on such date and has served continuously as a member of the Board of
Directors for a period of at least one year since the date of such Outside
Director's Initial Grant or the Automatic Grant Effective Date. Notwithstanding
anything in this Section 6.3 to the contrary, the Board of Directors may make
discretionary supplemental grants of Non-Qualified Options to an Outside
Director, provided, however, that no Outside Director may receive more than Five
Hundred Thousand (500,000) shares of Common Stock in any calendar year.

          (c) The exercise price of each Director Option will be 100% of the
fair market value of the shares of Common Stock subject to the Director Option
on the date such Director Option is granted.

          (d) Vesting.

               (i) Each Initial Grant will vest as determined by the Committee.

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               (ii) Notwithstanding any provision herein to the contrary, in the
event of a dissolution, liquidation or Change in Control of the Company, the
vesting of all Director Options will accelerate and such Director Options will
become exercisable in full prior to the consummation of such event at such times
and on such conditions as the Committee determines and must be exercised, if at
all, within three-months of the consummation of said event. Any Director Options
not exercised within such three-month period shall expire.

          (f)  The exercise period of Director Options shall not exceed ten
years from the date of grant, provided however, subject to the provisions of
Section 6.3 (g), no Director Option may be exercised more than 90 days after the
optionee ceases to serve as a member of the Board of Directors.

          (g)  If an Outside Director dies or becomes disabled (within the
meaning of Section 22(e)(3) of the Code or any successor provision thereto)
while a member of the Board of Directors, Director Options may be exercised (to
the extent otherwise exercisable on the date of disability or death) by such
disabled member of the Board of Directors or, in the case of death, by the
member of the Board of Directors' designated beneficiary, in each case within
the period of one year after the date of disability or death.

          7.   Terms and Conditions of Awards. The terms and conditions of each
Award granted under the Plan shall be specified by the Committee, in its sole
discretion, and shall be set forth in a written agreement between the
Participant and the Company, in such form as the Committee shall approve. The
terms and provisions of any Award granted hereunder need not be identical to
those of any other Award granted hereunder.

          The terms and conditions of each Award may include the following:

          (a)  The amount to be paid by a Participant to acquire the shares of
Common Stock pursuant to an Award shall be fixed by the Committee and may be
equal to, more than or less than 100% of the fair market value of the shares of
Common Stock subject to the Award on the date the Award is granted (but in no
event less than the par value of such shares).

          (b)  Each Award shall contain such vesting provisions, such transfer
restrictions and such other restrictions and conditions as the Committee, in its
sole discretion, may determine, including, without limitation, the circumstances
under which the Company shall have the right and option to repurchase shares of
Common Stock acquired pursuant to an Award.

                                       13
<PAGE>   14

          (c)  Stock certificates representing Common Stock acquired pursuant to
an Award shall bear a legend referring to any restrictions imposed on such Stock
and such other matters as the Committee may determine.

          (d)  To the extent that the Company is required to withhold any
Federal, state or local taxes in respect of any compensation income realized by
the Participant in respect of an Award granted hereunder, in respect of any
shares acquired pursuant to an Award, or in respect of the vesting of any such
shares of Common Stock, then the Company shall deduct from any payments of any
kind otherwise due to such Participant the aggregate amount of such Federal,
state or local taxes required to be so withheld, or if such payments are
insufficient to satisfy such Federal, state or local taxes, or if no such
payments are due or to become due to such Participant, then such Participant
will be required to pay to the Company, or make other arrangements satisfactory
to the Company regarding payment to the Company of, the aggregate amount of any
such taxes. All matters with respect to the total amount of taxes to be withheld
in respect of any such compensation income shall be determined by the Committee,
in its sole discretion.

          Section 8. Adjustments. (a) In the event that, after the adoption of
the Plan by the Board of Directors, the outstanding shares of the Company's
Common Stock shall be increased or decreased or changed into or exchanged for a
different number or kind of shares of stock or other securities of the Company
or of another entity in each such case through reorganization, merger or
consolidation, recapitalization, reclassification, stock split, split-up,
combination or exchange of shares or declaration of any dividends payable in
Common Stock, the Committee in good faith shall, subject to the provisions of
Section 8(c) below if the circumstances therein specified are applicable,
appropriately adjust (i) the number of shares of Common Stock (and the option
price per share) subject to the unexercised portion of any outstanding Option
(to the nearest possible full share); provided, however, that the limitations of
Section 424 of the Code shall apply with respect to adjustments made to ISOs,
(ii) the number of shares of Common Stock to be acquired pursuant to an Award
which have not become vested, and (iii) the number of shares of Common Stock for
which Options and/or Awards may be granted under the Plan, as set forth in
Section 4.1 hereof, and such adjustments shall be effective and binding for all
purposes of the Plan.

          (b)  If any capital reorganization or reclassification of the capital
stock of the Company or any consolidation or merger of the Company with another
entity, or the sale of all or substantially all its assets to another entity,
shall be effected in such a way that holders of Common Stock shall be entitled
to

                                       14
<PAGE>   15

receive stock, securities or assets with respect to or in exchange for Common
Stock, then, subject to the provisions of Section 8 (c) below if the
circumstances therein specified are applicable, each holder of an Option shall
thereafter have the right to purchase, upon the exercise of the Option in
accordance with the terms and conditions specified in the option agreement
governing such Option and in lieu of the shares of Common Stock immediately
theretofore receivable upon the exercise of such Option, such shares of stock,
securities or assets (including, without limitation, cash) as may be issued or
payable with respect to or in exchange for a number of outstanding shares of
such Common Stock equal to the number of shares of such Common Stock immediately
theretofore so receivable had such reorganization, reclassification,
consolidation, merger or sale not taken place.

          (c)  Notwithstanding Sections 8(a) and 8(b) hereof, in the event of
(i) any offer to holders of the Company's Common Stock generally relating to the
acquisition of all or substantially all of their shares, including, without
limitation, through purchase, merger or otherwise, or (ii) any proposed
transaction generally relating to the acquisition of substantially all of the
assets or business of the Company (herein sometimes referred to as an
"Acquisition"), the Board of Directors may, in its sole discretion, cancel any
outstanding Options (provided, however, that the limitations of Section 424 of
the Code shall apply with respect to adjustments made to ISO's) and pay or
deliver, or cause to be paid or delivered, to the holder thereof an amount in
cash or securities having a value (as determined by the Board of Directors
acting in good faith) equal to the product of (A) the number of shares of Common
Stock (the "Option Shares") that, as of the date of the consummation of such
Acquisition, the holder of such Option had become entitled to purchase (and had
not purchased) multiplied by (B) the amount, if any, by which (1) the formula or
fixed price per share paid to holders of shares of Common Stock pursuant to such
Acquisition exceeds (2) the option price applicable to such Option Shares.

          Section 9. Effect of the Plan on Employment Relationship. Neither the
Plan nor any Option and/or Award granted hereunder to a Participant shall be
construed as conferring upon such Participant any right to continue in the
employ of (or otherwise provide services to) the Company or any Subsidiary or
Parent thereof, or limit in any respect the right of the Company or any
Subsidiary or Parent thereof to terminate such Participant's employment or other
relationship with the Company or any Subsidiary or Parent, as the case may be,
at any time.

          Section 10. Amendment of the Plan. The Board of Directors may amend
the Plan from time to time as it deems desirable; provided, however, that,
without the approval of the holders of a majority of the outstanding capital
stock of the Company entitled to vote thereon or consent thereto, the Board of

                                       15
<PAGE>   16
Directors may not amend the Plan (i) to increase (except for increases due to
adjustments in accordance with Section 8 hereof) the aggregate number of shares
of Common Stock for which Options and/or Awards may be granted hereunder, (ii)
to decrease the minimum exercise price specified by the Plan in respect of ISOs
or (iii) to change the class of Employees eligible to receive ISOs under the
Plan.

          Section 11. Termination of the Plan. The Board of Directors may
terminate the Plan at any time. Unless the Plan shall theretofore have been
terminated by the Board of Directors, the Plan shall terminate ten years after
the date of its initial adoption by the Board of Directors. No Option and/or
Award may be granted hereunder after termination of the Plan. The termination or
amendment of the Plan shall not alter or impair any rights or obligations under
any Option and/or Award theretofore granted under the Plan.

          Section 12. Effective Date of the Plan. The Plan shall be effective as
of July 23, 1998, the date on which the Plan was adopted by the Board of
Directors and approved by the requisite holders of outstanding capital stock of
the Company.

                                    * * * * *

                                       16<PAGE>   1
                                                                   EXHIBIT 10.13

                    SECOND AMENDMENT dated as of March 8, 2000 (this
                    "Amendment") to the Credit Agreement dated as of June 29,
                    1999, as amended (the "Credit Agreement") by and among
                    LEXENT INC. (formerly known as National Network
                    Technologies, Inc.), a Delaware corporation (the "Company"),
                    EUROPEAN AMERICAN BANK, a New York banking corporation
                    ("EAB"), as Administrative Agent and the Lenders Party
                    Thereto.

WHEREAS, the Company has requested and the Administrative Agent and the Lenders
have agreed, subject to the terms and conditions of this Amendment, to amend
certain provisions to the Credit Agreement as set forth herein;

NOW, THEREFORE, in consideration of the premises and of the mutual agreements
herein contained, the parties hereto agree as follows:

1.   AMENDMENTS.

     (a)  The following defined terms are added to Section 1.01 in alphabetical
     order:

     "Permitted Acquisition" shall mean the acquisition by the Company or any
     Corporate Guarantor of the capital stock, membership interests or other
     ownership interests of a Person engaged in the same or similar business as
     the business of the Company or such Corporate Guarantor or the purchase of
     all or substantially all of the assets used by such Person in connection
     with such business or assets comprising a line of business or a division of
     such Person, provided in each case, (i) no Default or Event of Default
     shall have occurred and be continuing or would occur after giving effect to
     the acquisition, (ii) in the event of an acquisition of stock or of a
     membership interest of a Person, the Board of Directors or other governing
     body of such Person shall have recommended the sa1e by its shareholders or
     its members of their equity interest to the Company or the Corporate
     Guarantor, as the case may be, and (iii) Company shall have complied with
     the provisions of Section 6.13 hereof.

     "Qualifying IPO" shall mean an initial public offering of the Company's
     common stock pursuant to an effective registration statement on Form S-1
     pursuant to which the Company has received proceeds, net of underwriting
     fees and reasonable out-of-pocket expenses incurred in connection
     therewith, of not less than $65,000,000.

     (b)  The following defined terms are hereby amended and restated in their
     entirety to provide as follows:

     "Revolving Credit Commitment" shall mean with respect to each Lender the
     obligation of such Lender to make Revolving Credit Loans to the Company in
     aggregate amount not to exceed $6,000,000 with respect to SBLI and
     $14,000,000 with respect to EAB.

     "Revolving Credit Commitment Termination Date" shall mean June 30, 2003.

<PAGE>   2

     "Total Revolving Credit Commitments" shall mean, at any time, the aggregate
     of the Revolving Credit Commitments in effect at such time, which shall be
     initially $20,000,000.

     (c)  Section 2.01(f) is hereby amended in its entirety to provide as
     follows:

          "(f) Intentionally Omitted."

     (d)  Section 3.04(b) is hereby amended by deleting the reference to the
     phrase "1/8 of 1%" on the fifth line thereof and replacing it with the
     phrase "1/4 of 1%" in its place and stead.

     (e)  Section 3.07 is hereby amended in its entirety to provide as follow:

          "PRO RATA TREATMENT AND PAYMENTS. Each borrowing by the Company from
          the Lenders shall be made by the Lenders as follows: (a) up to the
          first $12,000,000 of Revolving Credit Loans made by the Lenders shall
          be allocated between the Lenders as follows: (i) 50% to SBLI and (ii)
          50% to EAB and (b) any requests for borrowings in excess of
          $12,000,000 shall be made solely by EAB. Each payment by the Company
          on account of any fee and any reduction of the Revolving Credit
          Commitment of the Lenders hereunder shall be made pro rata according
          to the respective relevant Commitment Proportions of the Lenders,
          provided that if the outstanding principal amount of the Revolving
          Credit Loans is greater than $12,000,000, then (a) that portion of the
          fee required to be paid pursuant to Section 3.04(b) which is allocable
          to that portion of the Revolving Credit Commitment which is in excess
          of $12,000,000 shall be paid solely to EAB for its account, with the
          balance of such such fee shared pro rata according the respective
          relevant Commitment Proportions of the Lenders and (b) any reduction
          of the Revolving Credit Commitment shall first reduce that portion of
          the Revolving Credit Commitment which is in excess of $12,000,000 and
          the balance thereof shall be be used to reduce the balance of the
          Revolving Credit Commitment. Each payment (including each prepayment)
          by the Company on account of principal of and interest on each Loan
          shall be made pro rata according to the respective outstanding
          principal amounts of such Loans held by each Lender; provided,
          however, if the outstanding principal amount of the Revolving Credit
          Loans is in excess of $12,000,000, then (i) all payments of principal
          received in respect to the Revolving Credit Loans shall be applied
          first to those Revolving Credit Loans in excess of $12,000,000 which
          were made solely by EAB, until the principal amount of all such
          Revolving Credit Loans have been paid in full and (ii) all prepayments
          shall first be applied to those Revolving Credit Loans which are in
          excess of $12,000,000 and which were funded solely by EAB. All
          payments (including prepayments) to be made by the Company on account
          of principal, interest, fees and reimbursement obligations shall be
          made without set-off or counterclaim and shall be made to the
          Administrative Agent, for the account of the Lenders (or EAB as set
          forth above) at the Payment Office of the Administrative Agent in
          Dollars in immediately available funds. The Administrative Agent shall
          distribute such payments to the Lenders promptly upon receipt in like
          funds by wire

                                        2
<PAGE>   3

              transfer of each Lender's portion of such payment to such Lender
              for the account of its Lending Office. The Administrative Agent
              may, in its sole discretion, directly charge principal and
              interest payments due in respect of the Loans to the Company's or
              any Corporate Guarantors' accounts at the Payment Office or other
              office of the Administrative Agent. Except as otherwise provided
              in the definition of "Interest Period", if any payment hereunder
              becomes due and payable on a day other than a Business Day, such
              payment shall be extended to the next succeeding Business Day,
              and, with respect to payments of principal, interest thereon shall
              be payable at the then applicable rate during such extension.

          (f) Section 6.03 is hereby amended to redesignate clause (l) as
          clause (m) and to add a new clause (l) which shall read in its
          entirety as follows:

              "Notify the Agent and Lenders of the consummation of a Qualifying
              IPO on the date thereof."

          (g) Section 6.03 is further amended to insert the following text at
          the beginning of clause (i):

              "Prior to consummation of a Qualifying IPO,"

          (h) Clause (j) of Section 6.03 is hereby amended and restated in
          its entirety to read as follows:

              "(j) (i) Prior to consummation of a Qualifying IPO, and after
              consummation of a Qualifying IPO if the aggregate principal amount
              of the Loans outstanding as of the end of the preceding month is
              equal to or greater than $5,000,000, as soon as available and in
              any event within twenty-one (21) days after the end of each
              month, detailed monthly schedules of accounts receivable and
              accounts payables aging and a revenue summary, each in form and
              substance satisfactory to the Lenders and, (ii) after
              consummation of a Qualifying IPO (but subject to clause (i)) as
              soon as available and in any event within twenty-one (21) days
              after the end of each fiscal quarter, detailed quarterly
              schedules of accounts receivable and accounts payables aging and
              a revenue summary, each in form and substance satisfactory to
              the Lenders."

          (i) Section 7.12 is hereby amended to delete all the text thereof
          commencing after the text "provided, however," and to add the text
          "the Company may consummate Permitted Acquisitions" in lieu thereof."

          (j) Section 7.14 is hereby amended to add the following text at the
              end thereof:

             "; provided, however, following the consummation of a Qualifying
             IPO the Company may prepay Subordinated Debt provided that after

                                       3

<PAGE>   4

              giving effect to each such payment no Default or Event of Default
              shall have occurred and be continuing, including, without
              limitation, any Default or Event of Defau1t pursuant to Section
              7.13."

          (k) Section 7.15 is hereby amended to add the following sentence at
          the end thereof:

              "Notwithstanding the foregoing, following consummation of a
              Qualifying IPO the Company may pay cumulative dividends with
              respect to its preferred stock accrued and unpaid for the period
              commencing January 1, 1999 through the date on which the
              Qualifying IPO is consummated provided no Default or Event of
              Default shall have occurred and be continuing or would occur
              after giving effect to such payment."

          (l) Section 8.01(k) is hereby amended to add the following text
          after the text "of record at least 51%":

              "or, following consummation of a Qualifying IPO, at least 40%,"

          (m) Clauses (a), (b), (c), (d), (e) and (f) of Section 7.13 are
          hereby deleted in their entirety and the following new clauses
          (a),(b), (c) and (d) are added in lieu thereof:

              "(a) Minimum Consolidated EBITDA.  Permit Consolidated EBITDA as
              of the last day of any calendar quarter to be less than the
              amount set forth below opposite the relevant calendar year:

<TABLE>
<CAPTION>
        Calendar Year                                         Amount
<S>                                                         <C>
        2000                                                     $15,500,000
        2001                                                     $20,000,000
        2002 and each calendar year thereafter                   $21,000,000
</TABLE>
              (b) Consolidated Fixed Charge Ratio. Permit the Consolidated Fixed
              Charge Ratio as of the last day of any calendar quarter to be
              less than the amount set forth below opposite the relevant
              calendar year:
<TABLE>
<CAPTION>
        Calendar Year                                        Ratio
<S>                                                          <C>
        2000                                                     2.0:1.00
        2001                                                     2.75:1.00
        2002 and each calendar year thereafter                   2.75:1.00
</TABLE>
          (d) Consolidated Tangible Net Worth Plus Subordinated Debt. Prior to
          consummation of a Qualifying IPO, permit Consolidated Tangible Net
          Worth plus Subordinated Debt, as of the last day of any calendar

                                       4

<PAGE>   5

          quarter, to be less than the amount set forth below opposite the
          relevant calendar year:

          <TABLE>
          <CAPTION>
          Calendar Year                                         Amount
          <S>                                                       <C>
          2000                                                      $17,500,000
          2001                                                      $25,000,000
          2002 and each calendar year thereafter                    $32,500,000
          </TABLE>

          After consummation of a Qualifying IPO permit Consolidated Tangible
          Net Worth plus Subordinated Debt, as of the last day of any fiscal
          quarter, commencing with the fiscal quarter in which the Qualifying
          IPO occurs to be less than $75,000,000.

          (e) Consolidated Leverage Ratio. Prior to consummation of a
          Qualifying IPO, permit the Consolidated Leverage Ratio as of the last
          day of any fiscal quarter to exceed the ratio set forth opposite the
          relevant calendar year:

          <TABLE>
          <CAPTION>
          Calendar Year                                           Ratio
          <S>                                                        <C>
          2000                                                        2.15:1.00
          2001                                                        1.85:1.00
          2002 and each calendar year thereafter                      1.45:1.00
          </TABLE>

    After consummation of a Qualifying IPO, permit the Consolidated Leverage
    Ratio to exceed 1.0:1.0 as of the end of any fiscal quarter commencing with
    the fiscal quarter in which the Qualifying IPO occurs.

    (n) Article 10 is hereby amended to add a new Section 10.14 which shall
    read as follows:

    Section 10.14. RELEASE OF GUARANTEES. The Administrative Agent and the
    Lenders agree that provided no Default or Event of Default shall have
    occurred and be continuing as of the date of the consummation of a
    Qualifying IPO, effective upon the consummation of a Qualifying IPO the
    Individual Guarantors shall be released from their Individual Guaranties.
    Following such release, the Administrative Agent and the Lenders shall
    upon request of the Company deliver to the Company for the benefit of the
    Individual Guarantors a writing confirming that the Individual Guarantors
    are released from their obligations under their respective Individual
    Guarantees;

    (o) Exhibit A to the Credit Agreement is hereby amended and restated and is
    replaced with Exhibit A attached to this Amendment.

2.  CONDITIONS TO EFFECTIVENESS. The amendments set forth herein are subject
to satisfaction of the following conditions on the date hereof:

                                       5
<PAGE>   6

          (a)      The  Administrative Agent shall have received a facility
    fee in the amount of $43,750, $13,125 of which shall be payable to SBLI
    and $30,625 of which shall be payable to EAB.

          (b)      Each Lender shall have received an original Amended and
    Restated Note, in the applicable form attached hereto as Exhibit A,
    with the appropriate insertions and duly executed by the Company.

          (c)      The Administrative Agent shall have been reimbursed
    for the reasonable legal fees of counsel incurred in connection with the
    preparation of the amendments.

          (d)      The Administrative Agent shall have received the following:

                   (i)      UCC search results identifying the financing
                            statements on file with respect to the Company;

                   (ii)     a certificate of the Secretary of the Borrower, (A)
                            attesting to all corporate action taken by the
                            Borrower, including resolutions of its Board of
                            Directors authorizing the execution, delivery and
                            performance of this Amendment and each other
                            document to be delivered pursuant to this Amendment;
                            (B) stating that, except as set forth in such
                            certificate, the corporate documents previously
                            delivered to the Lenders have not been amended,
                            modified, revoked or rescinded as of the date of
                            their prior certification and (C) certifying  the
                            names and true signatures of certain officers of the
                            Borrower authorized to sign this Amendment and the
                            other Loan Documents.

                   (iii)    a certificate of an Executive Officer of the
                            Borrower stating that, except as set forth in such
                            certificate with respect to a matter concerning the
                            representations contained in clause (a) of Section
                            4.06 of the Credit Agreement, the representations
                            and warranties in Article IV of the Credit Agreement
                            are true and correct on such date as though made on
                            and as of such date, unless such representation is
                            as of a specific date, in which case, as of such
                            date, and that no event has occurred as is
                            continuing which constitutes a Default or Event of
                            Default,

                   (iv)     such other documents, instruments, approvals,
                            opinions and evidence as the Lenders may reasonably
                            require.

    3.      MISCELLANEOUS.

    Capitalized terms used herein and not otherwise defined herein shall have
    the same meanings as defined in the Credit Agreement.

                                       6

<PAGE>   7

    Except as expressly amended hereby, the Credit Agreement shall remain in
    full force and effect in accordance with the original terms thereof.

    The amendments herein contained are limited specifically to the matters set
    forth above and do not constitute directly or by implication an amendment or
    waiver of any other provision of Credit Agreement or any default which may
    occur or may have occurred under the Credit Agreement.

    The Company hereby represents and warrants that (a) except as set forth in
    Schedule A hereto with respect to a matter concerning the representations
    contained in clause (a) of Section 4.06 of the Credit Agreement, after
    giving effect to this Amendment, the representations and warranties by the
    Company and each Corporate Guarantor pursuant to the Credit Agreement and
    the Loan Documents to which each is a party are true and correct in all
    material respects as of the date hereof with the same effect as those such
    representations and warranties have been made on and as of such date, unless
    such representation is as of a specific date, in which case, as of such
    date, (b) after giving effect to this Amendment, no Default or Event of
    Default has occurred and is continuing.

    This Amendment may be executed in one or more counterparts, each of which
    shall constitute an original, but all of which when taken together shall
    constitute but one Amendment. This Amendment shall become effective when
    duly executed counterparts hereof which, when taken together, bear the
    signatures of each of the parties hereto shall have been delivered to the
    Administrative Agent.

    This Amendment shall constitute a Loan Document.

                                       7

<PAGE>   8

    IN WITNESS WHEREOF, the Company,the Administrative Agent and the Lenders
    have caused this Amendment to be duly executed by their duly authorized
    officers, all as of the day and year first above written.

                                LEXENT INC. (formerly known as National Network
                                Technologies, Inc.)

                                By: /s/     JONATHAN H. STERN
                                    -------------------------
                                Name:  Jonathan H. Stern
                                Title: Executive Vice President, CFO

                                EUROPEAN AMERICAN BANK, as Administrative Agent
                                and as a Lender

                                By: /s/      ANDREW CUNNINGHAM
                                    --------------------------
                                Name:   Andrew Cunningham
                                Title:  Vice President

                                STATE BANK OF LONG ISLAND, as a Lender

                                By: /s/        MICHAEL SABALA
                                    -------------------------
                                Name:   Michael Sabala
                                Title:  Vice President

                                       8

<PAGE>   9
The undersigned, not as parties to the Credit Agreement, but as Guarantors under
the Guarantees, each dated as of June 29, 1999, do hereby accept and agree to
the terms of this Amendment and Waiver and further acknowledge that their
respective Guaranty is in full force and effect with respect to such Guarantor.

                                       NATIONAL NETWORK TECHNOLOGIES, LLC

                                       By /s/  JONATHAN H. STERN
                                         -----------------------
                                       Title:   Executive Vice President, CFO

                                       HUGH O'KANE ELECTRIC CO. LLC

                                       By:/s/  JONATHAN H. STERN
                                          ----------------------
                                       Title: Executive Vice President, CFO

                                       /s/  HUGH J. O'KANE JR.
                                         ----------------------
                                       Hugh J. O'Kane, Jr.

                                       /s/  KEVIN M. O'KANE
                                          ------------------
                                       Kevin M. O'Kane

                                       9

<PAGE>   10

                                    EXHIBIT A

                            AMENDED AND RESTATED NOTE

     $6,000,000                                           New York, New York
                                                        as of March   , 2000

          FOR VALUE RECEIVED, LEXENT INC. (f/k/a/ National Network Technologies,
Inc.), a Delaware corporation (the "Company"), promises to pay to the order of
STATE BANK OF LONG ISLAND (the "Lender"), on or before the Revolving Credit
Commitment Termination Date, SIX MILLION DOLLARS ($6,000,000) or, if less, the
unpaid principal amount of all Revolving Credit Loans made by the Lender to the
Company under the Credit Agreement referred to below. The Company also promises
to pay interest on the unpaid principal amount hereof from the date hereof until
paid in full at the rates and at the times which shall be determined in
accordance with the provisions of the Credit Agreement referred to below.

          This Note is the "Note" issued pursuant to and entitled to the
benefits of the Credit Agreement dated as of June 29, 1999 by and among the
Company, the Lender, European American Bank, as Agent for the Lenders and the
Lenders referred to therein (as the same may be amended, modified or
supplemented from time to time, the "Credit Agreement"), to which reference is
hereby made for a more complete statement of the terms and conditions under
which the Loan evidenced hereby was made and is to be repaid. Capitalized terms
used herein without definition shall have the meanings set forth in the Credit
Agreement.

          Each of the Lender and any subsequent holder of this Note agrees, by
its acceptance hereof, that before transferring this Note, it shall record the
date and amount of each payment or prepayment of principal of the Loan
previously made hereunder on the grid schedule annexed to this Note; provided,
however, that the failure of the Lender or holder to set forth the Loan,
payments and other information on the attached grid schedule shall not in any
manner affect the obligation of the Company to repay the Loan made by the Lender
in accordance with the terms of this Note.

          This Note is subject to optional prepayments pursuant to Section 3.03
of the Credit Agreement.

          Upon the occurrence of an Event of Default, the unpaid balance of the
principal amount of this Note, together with all accrued but unpaid interest
thereon, may become, or may be declared to be, due and payable in the manner,
upon the conditions and with the effect provided in the Credit Agreement.

          All payments of principal and interest in respect of this Note shall
be made in lawful money of the United States of America in immediately available
funds at the office of the Agent located at 335 Madison Avenue, New York, New
York 10017, or at such other place as shall be designated in writing for such
purpose in accordance with the terms of the Credit Agreement.

          This Note is an amendment and restatement of and is being issued in
replacement of

                                       10

<PAGE>   11

and in substitution for, the Note, dated as of June 29, 1999, in the original
principal amount of $5,000,000, issued by the Company to the order of the Lender
(the "Original Note"); provided, however, that all principal unpaid and all
interest accrued and unpaid under the Original Note shall be deemed to be
evidenced by this Note and payable hereunder from and after the date hereof.
The execution and delivery of this Note shall not be construed (i) to have
constituted repayment of any principal or interest on the Original Note or (ii)
to release, cancel, terminate or otherwise impair all or any part of the lien or
security interest granted to the Lender as collateral security for the Original
Note, all of which liens and security interests shall secure this Note.

          No reference herein to the Credit Agreement and no provision of this
Note or the Credit Agreement shall alter or impair the obligation of the
Company, which is absolute and unconditional, to pay the principal of and
interest on this Note at the place, at the respective times, and in the currency
herein prescribed.

          The Company and endorsers of this Note waive diligence, presentment,
protest, demand, and notice of any kind in connection with this Note.

          THIS NOTE SHALL BE GOVERNED BY, AND SHALL BE CONSTRUED AND ENFORCED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO PRINCIPLES
OF CONFLICTS OF LAW.

          IN WITNESS WHEREOF, the Company has caused this Note to be executed
and delivered by its duly authorized officer as of the day and year and at the
place first above written.

                              LEXENT INC. (f/k/a National Network
                              Technologies, Inc.)

                              By
                                  -------------------------------------
                              Name: Jonathan Stern

                              Title: Executive Vice President, CFO

                                       11
<PAGE>   12

                                    SCHEDULE

<TABLE>
<CAPTION>
         Amount of     Outstanding    Type                   Applicable     Amount of     Notation
         Principal     Principal      of        Interest     Interest       Principal     Made
Date     Payment       Balance        Loan      Rate         Period         Paid          By
----     -------       -------        ----      ----         ------         ----          --
<S>      <C>           <C>            <C>       <C>          <C>            <C>           <C>

</TABLE>

                                       12
<PAGE>   13

                            AMENDED AND RESTATED NOTE

$14,000,000                                                   New York, New York
                                                             as of March__, 2000

          FOR VALUE RECEIVED, LEXENT INC. (f/k/a National Network Technologies,
Inc.), a Delaware corporation (the "Company"), promises to pay to the order of
EUROPEAN AMERICAN BANK (the "Lender"), on or before the Revolving Credit
Commitment Termination Date, FOURTEEN MILLION DOLLARS ($14,000,000) or, if less,
the unpaid principal amount of all Revolving Credit Loans made by the Lender to
the Company under the Credit Agreement referred to below. The Company also
promises to pay interest on the unpaid principal amount hereof from the date
hereof until paid in full at the rates and at the times which shall be
determined in accordance with the provisions of the Credit Agreement referred to
below.

          This Note is the "Note" issued pursuant to and entitled to the
benefits of the Credit Agreement dated as of June 29, 1999 by and among the
Company, the Lender, European American Bank, as Agent for the Lenders and the
Lenders referred to therein (as the same may be amended, modified or
supplemented from time to time, the "Credit Agreement"), to which reference is
hereby made for a more complete statement of the terms and conditions under
which the Loan evidenced hereby was made and is to be repaid. Capitalized terms
used herein without definition shall have the meanings set forth in the Credit
Agreement.

          Each of the Lender and any subsequent holder of this Note agrees, by
its acceptance hereof, that before transferring this Note, it shall record the
date and amount of each payment or prepayment of principal of the Loan
previously made hereunder on the grid schedule annexed to this Note; provided,
however, that the failure of the Lender or holder to set forth the Loan,
payments and other information on the attached grid schedule shall not in any
manner affect the obligation of the Company to repay the Loan made by the Lender
in accordance with the terms of this Note.

          This Note is subject to optional prepayments pursuant to Section 3.03
of the Credit Agreement.

          Upon the occurrence of an Event of Default, the unpaid balance of the
principal amount of this Note, together with all accrued but unpaid interest
thereon, may become, or may be declared to be, due and payable in the manner,
upon the conditions and with the effect provided in the Credit Agreement.

          All payments of principal and interest in respect of this Note shall
be made in lawful money of the United States of America in immediately available
funds at the office of the Agent

                                       13
<PAGE>   14

located at 335 Madison Avenue, New York, New York 10017, or at such other place
as shall be designated in writing for such purpose in accordance with the terms
of the Credit Agreement.

          This Note is an amendment and restatement of and is being issued in
replacement of and in substitution for, the Note, dated as of June 29, 1999, in
the original principal amount of $7,500,000, issued by the Company to the order
of the Lender (the "Original Note"); provided, however, that all principal
unpaid and all interest accrued and unpaid under the Original Note shall be
deemed to be evidenced by this Note and payable hereunder from and after the
date hereof. The execution and delivery of this Note shall not be construed (i)
to have constituted repayment of any principal or interest on the Original Note
or (ii) to release, cancel, terminate or otherwise impair all or any part of the
lien or security interest granted to the Lender as collateral security for the
Original Note, all of which liens and security interests shall secure this Note.

          No reference herein to the Credit Agreement and no provision of this
Note or the Credit Agreement shall alter or impair the obligation of the
Company, which is absolute and unconditional, to pay the principal of and
interest on this Note at the place, at the respective times, and in the currency
herein prescribed.

          The Company and endorsers of this Note waive diligence, presentment,
protest, demand, and notice of any kind in connection with this Note.

          THIS NOTE SHALL BE GOVERNED BY, AND SHALL BE CONSTRUED AND ENFORCED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO PRINCIPLES
OF CONFLICTS OF LAW.

          IN WITNESS WHEREOF, the Company has caused this Note to be executed
and delivered by its duly authorized officer as of the day and year and at the
place first above written.

                                       LEXENT INC. (f/k/a National Network
                                       Technologies, Inc.)

                                       By
                                         ------------------------------------
                                       Name: Jonathan Stern
                                       Title: Executive Vice President, CFO

                                       14
<PAGE>   15
                                    SCHEDULE

<TABLE>
<CAPTION>
         Amount of     Outstanding    Type                   Applicable     Amount of     Notation
         Principal     Principal      of        Interest     Interest       Principal     Made
Date     Payment       Balance        Loan      Rate         Period         Paid          By
----     -------       -------        ----      ----         ------         ----          --
<S>      <C>           <C>            <C>       <C>          <C>            <C>           <C>

</TABLE>

                                       15
<PAGE>   16

                                   SCHEDULE A

                    In August 1999, a former employee of the Borrower filed a
                    charge of employment discrimination against the Borrower
                    with the New York State Division of Human Rights and the
                    Equal Opportunity Commission and has been granted a right to
                    sue in federal court. If suit is brought, management of the
                    Borrower is prepared to defend any claims vigorously and
                    believes that resolution of such claims should not have a
                    Material Adverse Effect (as such term is defined in the
                    Credit Agreement). However, although such former employee
                    has not to date asserted any claims for a specified sum of
                    money, any such claims, if asserted, could be for an amount
                    in excess of $200,000. Furthermore, although management of
                    the Borrower believes that any such claims should be covered
                    by insurance (other than reasonable and customary
                    deductibles), there is no assurance that such coverage will
                    be available.

                                       16

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