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                                                                  Exhibit 10.10

                                 LEASE AGREEMENT

                                 OFFICE BUILDING

         THIS LEASE AGREEMENT (hereinafter referred to as this "LEASE") dated
September 1, 2000 is made and entered into by and between 6715 Kenilworth Avenue
Partnership, a District of Columbia limited partnership(hereinafter referred to
as "Landlord"), having an office for purposes of notices hereunder at 1015 31st
Street N.W. Washington, DC, and Cogent Communications, Inc. a Delaware
corporation (hereinafter referred to as "Tenant"), having an office for purposes
of notices hereunder at 1015 - 31st Street, NW, Washington, D.C.

                              W I T N E S S E T H:

That for and in consideration of the rentals hereinafter reserved and of the
mutual covenants and agreements hereinafter set forth, Landlord and Tenant
hereby agree as follows:

                               CERTAIN DEFINITIONS

         1. As used in this Lease, the following terms shall have the following
meanings:

                  (a) BUILDING. The land, office building, and appurtenant
improvements, located at 1015 - 31st Street, N.W.,

                  (b) DEMISED PREMISES. The net rentable area of the Demised
Premises shall be approximately nineteen thousand six hundred (19,600) square
feet of space (1,450 square feet on the first floor, 2,800 square feet on the
third floor, 5,104 square feet on the fourth floor, 5,123 square feet on the
fifth floor, and 5,123 square feet on the sixth floor) in the Building (as
determined in accordance with the Washington Board of Realtors' standard method
of measurement) on the first (1st), third(3rd), fourth (4th), fifth (5th) and
sixth (6th) floors.

                  (c) LEASE TERM. A period of one (1) year (the "Lease Term",
commencing on a date which Landlord and Tenant intend to be on or about
September 1, 2000 hereinafter defined as the "Commencement Date") and expiring
at midnight on August 31, 2001 hereinafter referred to as the "Expiration
Date"). At the end of the Lease Term the Tenant shall have the option to renew
the Lease for a period of up to one year at the option of the Tenant.

                  (d) FIXED ANNUAL RENT. During the Lease Term, the aggregate
amount of Fixed Annual Rent due Landlord from Tenant shall be Four Hundred
Seventy Thousand Four Hundred and No/100 Dollars ($470,400) per Annum computed
on the basis of Twenty Four and No/100 Dollars ($24.00) per year per square feet
of space. The fixed Annual Rent due during the Lease Term shall be payable in
advance, without demand, notice, reduction or setoff, in equal monthly
installments of Thirty-nine Thousand Two Hundred and No/100 Dollars ($39,200)
(hereinafter referred to as the "Fixed Monthly Rent").

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                  (e) BUILDING RENTABLE AREA. The total rentable area in the
Building, as determined in accordance with the Washington Board of Realtors'
standard method of measurement, is agreed to be Twenty-Eight Thousand Six
Hundred Fifty-nine (28,659) square feet.

                  (f) Sixty eight percent (68%), being the proportion that the
square footage of the Demised Premises which is specified above bears to the
Building Rentable Area.

                  (g) Not used

                  (h) AGENT. The agent, if any, designated by Landlord from time
to time for management of the Building and collection of the sums due hereunder,
or any successor thereto appointed by Landlord. Tenant shall receive written
notice of the appointment of, or any change in, the Agent.

                  (i) REAL ESTATE TAXES. The total of all taxes and assessments
now or hereafter imposed, levied or assessed by any lawful authority upon or
against the land, buildings and all other appurtenant improvements constituting
the Building (whether such taxes and assessments are general, special or
otherwise, ordinary or extraordinary, foreseen or unforeseen), including
(without limitation) assessments for public and quasi-public improvements and
any tax or excise hereafter imposed specifically upon the rents or gross
receipts from the Building, but excluding any penalties, interest or other
charges assessed as a result of delinquent payment or non-payment of all such
aforesaid taxes and assessments. It is expressly understood and agreed that
"increases" in such Real Estate Taxes shall include any increase resulting from
a higher tax rate, from an increase in assessed valuation, from the imposition
of special assessments, or from any other cause whatsoever. "Tax Year" shall
mean the period (whether 12 months or less) with respect to which assessments of
Real Estate Taxes are made by the taxing authorities having jurisdiction. Real
Estate Taxes for each Tax Year shall be deemed to be the Real Estate Taxes
payable in respect of such Tax Year, even though the levy or assessment thereof
may be made during different Tax Years. Reasonable expenses, including
attorneys' fees and expert witness fees, incurred by Landlord in attempting to
obtain a reduction of real Estate Taxes shall be added to and included in the
amount of Real Estate Taxes, however, Landlord shall have no obligation to
contest any levy or imposition of any Real Estate Taxes and may settle,
compromise or abandon any contest with respect to the amount of any Real Estate
Taxes in its sole discretion. Refunds of Real Estate Taxes received by Landlord,
if any, shall accrue proportionately to Tenant's benefit in accordance with
Tenant's space fraction in the Building.

Tenant is responsible for paying its portion of Real Estate Taxes. The Tenants'
portion of Real Estate Taxes will be based upon the Tenants' Space Fraction
times the Real Estate Taxes assessed against the Building pro-rated for the
Lease Term.

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                  (j) LEASE YEAR. The first Lease year during the Lease Term
shall be the period commencing at midnight on the day immediately preceding the
Commencement Date and terminating at midnight on the last day of the twelfth
(12th) full calendar month thereafter. Each subsequent Lease Year during the
Lease Term shall commence on the day immediately following the last day of the
preceding Lease Year and shall continue for a period of twelve (12) full
calendar months, except that the last Lease Year during the Lease Term shall
terminate on the date that this Lease expires or is terminated.

                  (k) Not used

                  (l) Not used

                  (m) Not used

                  (n) Not used

                                 DEMISING CLAUSE

         2. Landlord does hereby lease and demise the Demised Premises to
Tenant, and Tenant does hereby hire, lease and take the Demised Premises from
Landlord, for the Lease Term and upon the covenants and conditions herein set
forth.

                                      TERM

         3. The term of this Lease shall be the Lease Term defined in Section
l(c) above. Tenant hereby covenants and agrees to accept the Demised Premises on
the Commencement Date and to surrender possession thereof on the Expiration Date
or upon any other termination of this Lease.

                                      RENT

         4. The Tenant covenants and agrees to pay rent to Landlord for use of
the Demised Premises, without notice or demand from Landlord and without
deduction, setoff, or counterclaim by Tenant, except as otherwise set forth
herein, as follows:

                  (a) The Tenant shall pay to the Landlord a Fixed Annual Rent
in the amount of $470,000.00 payable without deduction or set off in equal
monthly installments (hereinafter referred to as Fixed Monthly Rent) of
$39,200.00 in advance, the first installment of which is due and payable upon
the commencement date of this Lease, with subsequent installments due and
payable on the first day of each calendar month thereafter until the total rent
provided for herein is fully paid. If the commencement date is a day other than
the first day of the month, all rent shall be adjusted to the first day of the
month. The Tenant shall pay said rent to Landlord at the office of Agent, or to
such other party and/or at such other address as Landlord may designate from
time to time by written notice to Tenant. If Landlord shall at any time accept a
payment of rent after it shall

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become due and payable, such acceptance shall not excuse delay upon subsequent
occasions or be construed as a waiver of any of Landlord's rights hereunder with
respect to such late payment.

                  (b) Not used

                  (c) If any installment of rent accruing hereunder or other
sums payable hereunder shall not be paid within ten (10) days of the due date,
the rental and such other sums shall be increased, without affecting any of the
Landlord's other rights under this Lease, by a late rental charge equal to five
percent (5%) of the delinquent installment. No payment by Tenant or receipt by
Landlord of a lesser amount than the monthly installment of rent herein
stipulated shall be deemed to be other than on account of the earlier stipulated
rent, nor shall any endorsement or statement on any check or any letter
accompanying any check or payment as rent be deemed an accord and satisfaction,
and Landlord may accept such check without prejudice to Landlord's right to
recover the balance of such rent or pursue any other remedy provided in this
Lease.

                  (d) Not used

                  (e) Tenant's obligation to pay any rents reserved and other
amounts payable hereunder which have not been fully liquidated and established
as of the Expiration Date or other termination of this Lease shall survive
termination hereof.

                         USE: ASSIGNMENT AND SUBLETTING

         5.       (a) Tenant will use and occupy the Demised Premises solely for
general office purposes in accordance with applicable zoning regulations. The
Demised Premises will not be used for any other purpose whatsoever without the
prior written consent of Landlord, which consent shall not be unreasonably
withheld. Tenant will not use or occupy the Demised Premises for any unlawful,
disorderly, or extra-hazardous purpose and will comply with all present and
future laws, ordinances, regulations and orders of governmental entities having
jurisdiction over the Demised Premises or the Operation thereof.

                  (b) Tenant (i) will not assign, transfer, mortgage, or
encumber this Lease without the prior written approval of Landlord, in its sole
discretion, and (ii) will not sublet or rent (or permit occupancy or use of) the
Demised Premises or any part thereof, without the prior written consent of
Landlord as to each prospective sublessee, or other transferee, which consent
shall not be unreasonably withheld in the case of a sublease or other transfer
pursuant to which Tenant remains obligated to Landlord hereunder. It is
expressly agreed that Tenant shall have the right to sublet, subrent or permit
the use and occupancy of all or any part of the Demised Premises, provided that
Tenant furnishes written notice thereof to Landlord, Tenant remains fully
obligated to Landlord's consent, not to be unreasonably withheld or delayed. No
such

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assignment, transfer, or subletting shall be effectuated by operation of law or
otherwise without the prior written consent of Landlord given in accordance with
the provisions of this Section 5 (b). Tenant hereby agrees that Landlord shall
have the absolute right, without compensation to or subsequent consent from
Tenant, to deal directly with and to relet such portion (including all) of the
Demised Premises for Landlord's own account to any prospective assignee,
sublessee, or other transferee of tenant; provided, however, that Landlord shall
release Tenant from its obligations hereunder to the extent that Landlord relets
the Demised Premises to any such party. No consent by Landlord to any
assignment, transfer, or subletting shall be construed as a waiver or release of
Tenant from any of the terms of conditions of this Lease or from the requirement
of again obtaining Landlord's consent to any further assignment, transfer, or
subletting unless such consent of Landlord expressly so states. For the purposes
of this Lease, the following events (whether accomplished in one transaction or
a series of transactions) shall be deemed to be a subletting, transfer or
assignment of the Demised Premises or of this Lease: W any sale, transfer or
other conveyance of stock or voting rights, or creation of new stock or voting
rights, so as to alter or transfer effective control of a corporate tenant; or
(ii) a conveyance or transfer of partnership interests, or the creation of new
partnership interests, so as to alter or transfer effective control of a tenant
which is a general or limited partnership.

         6. Not Used

                                   ALTERATIONS

         7.       (a) Tenant shall not make any structural alterations,
improvements or additions to the Premises without first obtaining the written
consent of the Landlord, which consent shall not be unreasonably withheld or
delayed. All alterations and improvements made by Tenant shall remain upon the
Premises at the expiration or earlier termination of this Lease and shall become
the property of the Landlord, unless the Landlord shall, prior to termination of
this Lease, provide written notice to Tenant to remove the same, in which event
Tenant shall remove such alterations, improvements and/or additions and restore
the Premises to the same good order and condition in which it was at the
commencement of this Lease. If Tenant fails so to do, Landlord may do so,
collecting at Landlord's option the costs and expenses thereof from Tenant as
additional rent.

                  (b) If, notwithstanding the foregoing, any mechanic's lien is
filed against the Demised Premises, or the real property of which the Demised
Premises are a part, for work claimed to have been done for Tenant or materials
claimed to have been furnished to Tenant, then such mechanic's lien shall be
discharged by Tenant within ten (10) days thereafter, at Tenant's sole cost and
expense, by the payment thereof or by filing any bond required by law. If Tenant
shall fail to discharge any such mechanic's lien, Landlord may (at its option)
discharge the same and treat the cost thereof as additional rent payable with
the installment of fixed Monthly Rent next becoming due,

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but such discharge by Landlord shall not be deemed to waive or cure the default
of Tenant in not discharging the same. Tenant shall indemnify and hold harmless
Landlord from and against any and all expenses, liens, claims or damages to
person or property which may arise by reason of the making of any such
alterations, decorations, additions or improvements.

                  (c) If any such major alteration, addition or improvement is
made without the prior written consent of Landlord, Landlord shall, upon being
notified of such work, either consent to, or notify, Tenant in writing to
correct or remove the same, and if within ten (10) business days of receipt of
said notice, Tenant fails to so correct or remove the same, Tenant shall be
liable for any and all expenses incurred by Landlord in so doing. Any permitted
alterations, additions for improvements shall conform to all requirements and
regulations of applicable codes and regulations of any Board of Fire
Underwriters having jurisdiction.

                  (d) All alterations, additions or improvements in or to the
Demised Premises or the Building made by either party shall immediately become
the property of Landlord and shall remain upon and be surrendered with the
Demised Premises as a part thereof upon the expiration or other termination of
this Lease without disturbance, molestation or injury; provided, however, that
if Tenant is not in default in the performance of any of its obligations under
this Lease, Tenant shall have the right to remove, prior to the expiration or
other termination of this Lease, all trade fixtures, movable furniture,
furnishings or equipment installed in the Demised Premises at Tenant's expense.
If such property of Tenant is not remove by Tenant prior to the expiration or
other termination of this Lease, then Landlord shall have the right to remove
and store the same at Tenant's expense; and if such property is not removed
within five (5) days after delivery of written notice to Tenant that such
property has not been removed despite termination of this Lease, then the same
shall become the property of Landlord and shall be surrendered with the Demised
Premises as a part thereof.

                        TENANT'S EQUIPMENT AND OPERATIONS

         8.       (a) Tenant shall not conduct or permit the conduct of any
activity, or place any equipment or materials in or about the Demised Premises,
which will in any way either (i) increase the rate of fire or other insurance on
the Building; (ii) injure, obstruct or interfere with the rights of other
tenants or other persons having business at the Building; or (iii) conflict with
the applicable local, state, or federal fire or other laws of regulations. If
any increase in the rate of fire or other insurance shall be stated by any
insurance company or by the applicable Insurance Rating Bureau to be due to
Tenant's activity or equipment in or about the Demised Premises, such statement
shall be conclusive evidence that the increase in such rate is due to such
activity, materials or equipment, and as a result thereof, Tenant

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shall be liable for such increase and shall reimburse Landlord therefore.

                    MAINTENANCE BY TENANT: DAMAGE TO PREMISES

         9. Except as otherwise provided in this Lease, Tenant hereby accepts
the Premises in its condition existing on the commencement date of the Lease,
subject to all applicable zoning, municipal, county and state laws, ordinances,
rules and regulations governing and regulating the use of the Premises. Property
is leased in "AS-IS" condition.

                  (a) Tenant shall keep the Demised Premises and the fixtures
and equipment therein in clean, safe and sanitary condition; shall take good
care of the suffer no waste or injury thereto; and shall, at the expiration or
other termination of this Lease, surrender the same broom clean in the same
order and condition in which they are on the Commencement Date, ordinary wear
and tear and damage by the elements, fire and other casualty not due to Tenant's
negligence excepted. Tenant shall immediately notify Landlord of, and Tenant
shall repair, at Tenant's sole expense (i) any damage to the Building or the
Demised Premises which is caused by moving Tenant's property into, in or out of
the Building and/or the Demised Premises; (ii) any breakage caused by Tenant,
its agents, servant, employees, and business invitees of Tenant; and (iii) any
damage caused by fire or other casualty due to the negligence of Tenant, its
agents, servants, employees, and business invitees; provided that all such
repairs which are structural in nature, or which affect portions of the Building
other than the Demised Premises, shall be performed by Landlord (at the expense
of Tenant). If Tenant fails to make such repairs promptly after the receipt of a
written request from Landlord, Landlord shall have the right to make necessary
repairs, alterations and replacements. Any charge or cost incurred by Landlord
in making repairs for which Tenant is liable shall be paid by Tenant as
additional rent due and payable with the installment of Fixed Monthly Rent ( or
applicable renewal rent payment, if any) next falling due. This provision shall
be construed as an additional remedy granted to Landlord and not in limitation
of any other rights and remedies which Landlord has or may have in such
circumstances.

                  (b) Not used

                                   FURNISHINGS

         10. Landlord shall have the right to prescribe the weight and position
of safes and other heavy equipment or fixtures located in the Demised Premises.
No furniture, equipment or other bulky matter of any description will be
received into the Building or carried in the elevators except as approved by the
Landlord. All moving of furniture, equipment and other material shall be under
the direct control and supervision of Landlord, who shall, however, not be
responsible for any damage to or charges for moving the same. Tenant agrees
promptly to remove from the sidewalks, drives, and grounds adjacent to the

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Building any of the Tenant's furniture, equipment or other material there
delivered or deposited.

                    TENANT'S INSURANCE; WAIVER OF SUBROGATION

         11. If either party is paid any proceeds under any policy of insurance
naming such party as an insured, on account of any loss, damage or liability,
then such party hereby releases the other party, to the extent of the amount of
such proceeds, from any and all liability for such loss, damage or liability,
notwithstanding of such loss, damage or liability may arise out of the negligent
act or omission of the other party; provided that such release shall be
effective only with respect to loss or damage occurring during such time as the
appropriate policy of insurance of the releasing party provides that such
release shall not impair the effectiveness of such policy of the insured's
ability to recover thereunder. Each party hereto shall use reasonable efforts to
have a clause to such effect included in its insurance policies, and shall
promptly notify the other if such clause cannot be included in any such policy.

                                   INSPECTION

         12. Upon reasonable prior written notice from the Landlord or Agent,
except in the event of an emergency where no such written notice shall be
required, Tenant will allow the Landlord, Agent and their agents and employees
to enter the Demised Premises at all reasonable times, without charge therefor
or diminution of rent, for any of the following purposes: (i) to examine,
inspect or protect the Demised Premises; (ii) to prevent damage or injury to the
Demised Premises or to any other portion of the Building; (iii) to make such
repairs as the Landlord may deem reasonably necessary; or (iv) during the last
six (6) months of the Lease Term or any renewal term provided for hereunder, to
enter the Demised Premises during normal business hours to show the Demised
Premises to prospective tenants so long as Landlord does not unreasonably
interfere with Tenant's business operations.

                              ESTOPPEL CERTIFICATES

         13. At any time upon five (5) days prior request therefor by Landlord
and without charge therefore, Tenant shall execute, acknowledge and deliver to
Landlord a written estoppel certificate, in recordable form, certifying the
following to Landlord and any other persons designated by Landlord, as of the
date of such estoppel certificate: (i) that Tenant is in possession of the
Demised Premises, has unconditionally accepted the same, and is currently paying
the rent and additional rent reserved hereunder (or such state of facts as then
exists); (ii) that this Lease is unmodified and in full force and effect (or if
there has been a modification, that this Lease is in full force as modified and
setting forth such modifications); (iii) whether or not there are then-existing
any setoffs, abatements, or defenses against the enforcement of any right or
remedy of Landlord, or any duty or obligation of Tenant hereunder (and, if so,
specifying the same in detail); (iv) the dates, if any, to which any rent or
other charges have been paid in advance; (v) that Tenant has no knowledge of any
uncured defaults on the part of Landlord under this Lease (or if Tenant has
knowledge of any such uncured defaults, specifying

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the same in detail); and (vi) that Tenant has no knowledge of any event having
occurred that authorizes the termination of this Lease by Tenant (or if Tenant
has such knowledge, specifying the same in detail).

         14. Not used.

                                EVENTS OF DEFAULT

         15. The occurrence of any of the following shall constitute an event of
default hereunder:

                  (a) Failure of Tenant to pay, within ten (10) days any
installment of the Fixed Monthly Rent hereunder or any other sum herein required
to be paid by Tenant;

                  (b) Vacation or desertion of the Premises or permitting the
same to be empty and unoccupied for more than thirty (30) days;

                  (c) Tenant's failure to perform any other covenant or
condition of this Lease within thirty (30) days after written notice and demand,
unless the failure is of such a character as to require more than thirty (30)
days to cure, in which event Tenant's failure to proceed diligently to cure such
failure shall constitute an event of default;

                  (d) Tenant shall become insolvent, make an assignment for
benefit of creditors, make a transfer in fraud or creditors, file a petition of
bankruptcy under the National Bankruptcy Act, or if an involuntary petition
under said Act is filed against Tenant or if a receiver or trustee is appointed
for substantially all of Tenant's assets;

                  (e) The estate created hereby shall be taken on execution or
other process of law;

                  (f) Tenant shall be in default under any of the terms and
provision of the Initial Lease.

                       REMEDIES UPON DEFAULT: ENFORCEMENT

         16. Upon the occurrence of any event of default, Landlord may, at
Landlord's sole option, exercise any or all of the following remedies, together
with any such other remedies as may be available to Landlord at law or in
equity:

                  (a) Landlord may terminate this Lease by giving Tenant written
notice of its election to do so, as of a specified date not less than fifteen
(15) days after the date of the giving of such

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notice and this Lease shall then expire on the date so specified and Landlord
shall be then entitled to immediately regain possession of the demised Premises
as if the date had been originally fixed as the expiration date of the terms of
this Lease. Landlord may then reenter upon the leased Premises either with or
without process of law and remove all persons therefrom, the statutory notice to
quit or any other notice to quit being hereby expressly waived by Tenant. Tenant
expressly agrees that the exercise by Landlord of the right of reentry shall not
be a bar to or prejudice in any way other legal remedies available to Landlord.
In that event, Landlord shall be entitled to recover from Tenant as and for
liquidated damages an amount equal to the difference between the rent and
additional rent reserved in this Lease for the entire unexpired portion of the
term thereof and the fair rental value of the demised Premises for the same
period of time. Nothing herein contained, however, shall limit or prejudice the
right of Landlord to prove for and obtain as liquidated damages, by reason of
such termination, an amount equal to the maximum allowed by any statute or rule
of law in effect at the time when, and governing the proceedings in which, such
damages are to be proved, whether or not such amount be greater, equal to, or
less than the amount of the difference referred to above, and Landlord may in
its own name but as agent for Tenant re-let the demised Premises for any period
equal to or greater or less than the remainder of the original term of this
Lease, for any such which it may deem reasonable, to any other lessee which
Landlord may select, and for any purpose which Landlord may designate. Landlord
will make reasonable efforts to relet the Premises, and will allow Tenant to
find a new tenant. Any recovery by the Landlord shall be limited to the
difference in rent hereunder (plus any costs incurred in re-letting) and the
rent actually paid by the new tenant.

                  (b) No termination of this Lease nor any taking or recovery of
possession of the demised Premises shall deprive Landlord of any of his remedies
or actions against Tenant for past or future rent, nor shall the bringing of any
action for rent or breach of covenant, or the resort to any other remedy herein
provided for the recovery of rent be construed as a waiver of the right to
obtain possession of the Premises.

                  (c) In addition to any damages becoming due under subparagraph
(a) hereof, Landlord shall be entitled to recover from Tenant and Tenant shall
pay to Landlord an amount equal to all expenses, if any, incurred by the
Landlord in recovering possession of the demised Premises, and all reasonable
costs and charges for the care of said Premises while vacant, which damages
shall be due and payable by Tenant to Landlord at such time or times as such
expenses are incurred by the Landlord.

                  (d) In the event of a default or threatened default by Tenant
of any of the terms or conditions of this Lease, Landlord shall have the right
of injunction and the right to invoke any remedy allowed by law or in equity as
if no specific remedies of Landlord were set forth in this Lease.

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                  (e) It is further provided that if, under the provisions of
this Lease, default be made and a compromise and settlement shall be had
thereupon, it shall not constitute a waiver of any covenant herein contained,
nor of the Lease itself; and it is hereby specifically agreed that this Lease
shall not merge in any judgment had upon the same if compromise or settlement be
made upon said judgment prior to termination of Tenant's possession, the Lease
in such event to continue by the payment of rent herein reserved, and the
further performance of the covenants herein contained on the part of Tenant.

                 LANDLORD'S RIGHT TO CURE; LATE PAYMENT PENALTY

         17.      (a) If Tenant defaults in the performance of any of its
obligations hereunder, other than its obligations to pay rent or other sums due
and payable to Landlord under the terms of this Lease, and fails to cure such
default(s) after notice thereof, as providing in Section 16 above, Landlord may
(but shall not be required to) perform the same on behalf of Tenant, whereupon
the cost to Landlord therefor, plus interest from the date paid by Landlord at
the rate of eighteen percent (18%) per annum (or the maximum permissible rate
under applicable law, if lesser) shall be paid by Tenant to Landlord as
additional rent hereunder, due and payable with the installment of Fixed Monthly
Rent or other applicable rental payment, if any, next falling due; provided,
however, that such performance by Landlord shall not operate to cure such
default or to stop Landlord from pursuing of any remedy to which Landlord would
otherwise be entitled.

                  (b) In the event that Tenant fails to pay any installment of
rent within ten (10) business days after the same becomes due and payable shall
be subject to a late payment charge equal to five percent (5%) of the payment
not made when due; such late payment charge shall constitute additional rent
hereunder and shall be payable with the installment of delinquent installment of
rent.

                               TENANT HOLDING OVER

         18. Tenant shall surrender possession of the Demised Premises, broom
clean, upon expiration or other termination of this Lease. If Tenant shall
continue to remain in possession of the Demised Premises after the expiration or
other termination of this Lease with the knowledge and consent of Landlord, then
the following provisions shall apply: (i) Tenant shall automatically become a
tenant by the month at the Fixed Monthly Rent (as adjusted), or other applicable
rental payment, for the initial thirty (30) days of such holdover period; and
otherwise on all of the terms and provisions hereof; (ii) said monthly tenancy
shall commence with the first day following the end of the Lease Term; (iii)
Tenant shall be required to give Landlord at least thirty (30) days written
notice of any intention to quit; and (iv) Tenant shall be entitled to thirty
(30) days written notice to quit, except that in the event of nonpayment of rent
in advance or of the breach of any other covenant by Tenant, Tenant shall not be
entitled to any notice to quit, the usual thirty (30) days notice to quit being

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hereby expressly waived. Notwithstanding the foregoing, however, if Tenant shall
hold over after the expiration or termination of this Lease and Landlord desires
to regain possession of the Demised Premises promptly at the expiration thereof,
than at any time prior to Landlord's acceptance of rent from Tenant as a monthly
tenant hereunder, Landlord may elect to re-enter forthwith and take possession
of the Demised Premises without process, or by any legal process permitted under
applicable law.

                             UTILITIES AND SERVICES

         19. Tenant, during the term of this Lease, shall not pay for its own
gas, water, electricity, sewer, refuse disposal, and all other utility services
used by it on the Premises. Tenant will, during the term of the lease, pay for
its own telephone usage. Landlord shall in no event be liable for any
interruption or failure of utility services on the Premises.

                              LANDLORD'S LIABILITY

         20. Landlord and Agent assume no liability or responsibility whatever
with respect to the operation of Tenant's business in the Demised Premises or
with respect to any loss or damage (or whatever kind and however caused) to the
personal property documents, records, monies, or goods of Tenant or to anyone in
or about the Demised Premises by consent of Tenant; and the Tenant agrees to
hold the Landlord and Agent harmless against all such claims.

                                  CONDEMNATION

         21.      (a) If the whole of the demised Premises shall be taken by any
governmental or quasi-governmental authority under the power of condemnation,
eminent domain or expropriation, or in the event of conveyance in lieu thereof,
the term of the Lease shall cease as of the day possession shall be taken by the
governmental authority, and the entire award shall be the property of the
Landlord, except for the value of any fixtures or equipment installed by Tenant.

                  (b) In the event there in any taking by governmental or
quasi-governmental authority of a portion of the Premises which does not
seriously and adversely affect the ability of the Tenant to conduct its business
on the Premises, the Lease shall remain in full force and effect, and the
Tenant's rent shall be equitably adjusted based on the reduction in area of the
Premises.

                               LIABILITY INSURANCE

         22. At all times during the term hereof, or any extension thereof,
Tenant, at its own expense, shall maintain and keep in force for the mutual
benefit of Landlord and Tenant, general public liability insurance against
claims for personal injury, death or property damage occurring in or about the
Premises or sidewalks or areas adjacent to the Premises to afford protection to
the limit of

<Page>

not less than One Million Dollars and N0/100 ($1,000,000.00) with respect to
injury or death of a single person, or any accident, and to the limit of not
less than One Million Dollars and N0/100 ($1,000,000.00) with respect to
property damage. The policy or policies shall name the Landlord as an additional
insured. In order to evidence the coverage in effect, the Tenant shall provide
the Landlord with a Certificate of Insurance, and will obtain a written
obligation from the insurer to notify Landlord in writing at least ten (10) days
prior to cancellation or refusal to renew any such policies.

                                 INDEMNIFICATION

         23. Except for such intentional or negligent acts, Tenant shall
indemnify and save Landlord harmless from and against any and all liability,
claims, damages, penalties or judgments arising from or in any way connected
with injury to person or property sustained by action, in and about the
Premises, in custody and control of Tenant during the term of this Lease. If
Landlord shall, without fault of its own, be made a part of any litigation
commenced by or against Tenant, Tenant shall protect and hold Landlord harmless
and pay all costs, expenses and reasonable attorneys' fees that may be incurred
or paid by Landlord in enforcing the covenants and agreements of this Lease.

                                 BINDING EFFECT

         24. It is agreed that this Lease shall be binding upon and inure to the
benefits of the Landlord and Tenant and their successors and assigns. Subject to
any provisions hereof, restricting assignment or subletting by Tenant, this
Lease shall bind the parties, their personal representatives, successors and
assigns. This Lease shall be governed by the laws of the District of Columbia.

                               RIGHTS OF MORTGAGEE

         25. Mortgagee shall have the following rights:

                  (a) Any notice required to be given to the Landlord by the
Tenant shall be given as well, in the same manner to the Mortgagee.

                  (b) In the event that Tenant shall have any excuse from paying
rent or right to set off its expenses from the rent as a result of any default
by the Landlord or shall have any expense from the performance of any obligation
imposed upon Tenant by the terms of this Lease, then and in such event the
Tenant shall give notice of its intended exercise of such right in the manner
provided for herein to the Mortgagee and thereafter the Mortgagee shall have the
right but not the obligation to cure said defaults within the time provided for
cure of the same as set forth in this Lease.

                  (c) Upon the request of the Mortgagee, the Tenant will furnish
an Estoppel Certificate certifying to the rent paid and to be paid the remaining
term of the Lease, the existence of defaults of the

<Page>

Landlord, if any, and such other information concerning this tenancy as
Mortgagee may from time to time require.

                                   LEGAL FEES

         26. If either party named herein brings an action to enforce the terms
hereof or declare rights hereunder, the prevailing party and any such action on
trial or appeal, shall be entitled to his reasonable attorneys' fees to be paid
by the losing party as fixed by the Court.

                               TENANT IMPROVEMENTS

         27. Landlord hereby grants unto Tenant the right to install
improvements, all of which shall be installed at the sole cost and expense of
Tenant. All such improvements shall be installed in a good workmanlike manner,
and Tenant shall indemnify and save harmless Landlord from any liability of any
kind in connection with the installation of said improvements.

         28. Not used

                           FINAL AND ENTIRE AGREEMENT

         29. This Lease contains the final and entire agreement between the
parties, and they shall not be bound by any terms, conditions or representations
not contained herein.

                                    ADDENDUM

         30. The provisions of any Addendum hereto attached and signed by the
parties shall be considered a part of this Lease.

                                     NOTICES

         31. All notices required under this Lease shall be given in writing and
shall be deemed to be properly served if sent by certified or registered mail to
the following addresses:

                  TO LANDLORD:           6715 Kenilworth Avenue Partnership
                                         1015 31st Street, N.W.
                                         Washington, D.C.

                  TO TENANT:             Cogent Communications, Inc
                                         1015 31st Street, N.W.
                                         Washington, D.C. 20007
                                         Attn: Thaddeus G. Weed - Controller

                              TERMINATION OF LEASE

         32. Not used.

<Page>

                                  MISCELLANEOUS

         33. This Lease cannot be changed orally, but only by a writing signed
by the party or parties to be charged thereby. The invalidity or illegality of
any provision of this Lease shall not affect the validity of the other
provisions hereof. The captions and headings contained herein are for reference
and convenience only. This Lease shall be construed in accordance with the laws
of the District of Columbia. Each of the parties hereto hereby warrants and
certifies to the other that it has full power and authority to enter into this
Lease; each individual executing this Lease certified to the other party hereto
that he or she has the right, power, capacity and authority to bind the entity
on whose behalf he or she is executing the Lease. If Tenant is more than one
person or entity the persons or entities comprising Tenant shall be jointly and
severally liable hereunder. This Lease may be executed in multiple original
counterparts, each of which shall be deemed to be an original but all of which
shall constitute one and the same agreement. The submission of this Lease to
Tenant for examination shall not constitute a reservation of or an option to
rent the Demised Premises; this Lease shall become effective and binding on
Landlord only upon full execution hereof by Landlord.

                              ADDITIONAL PROVISIONS

         34. Not used

         IN WITNESS WHEREOF, the parties have signed this Lease Agreement on the
date first herein above written.

LANDLORD:

                  /s/
------------------------------------

By:      DAVE SCHAEFFER
   ---------------------------------

TENANT:

By:               /s/
   ---------------------------------

DATE:

         AUGUST 30, 2000
------------------------------------<Page>

                                                                   Exhibit 10.11

c  o  g  e  n  t
   C O M M U N I C A T I O N S                BRILLIANTLY FAST. ELEGANTLY SIMPLE
--------------------------------------------------------------------------------

6715 Kenilworth Avenue Partnership
1015 31st Street, NW
Washington, DC 20007

Re: Lease Agreement Term: Sept 1, 2000 - 8/31/2001
Cogent Communications, Inc-
1015 31st Street, NW, Washington, DC 20007

Dear Mr. Schaeffer,                                August 1, 2001

         In reference to the above subject Lease Agreement between Cogent
Communications, Inc. (Tenant) and 6715 Kenilworth Avenue Partnership (Landlord),
Cogent Communications, Inc. elects to extend the lease, at the location
referenced above, and per the conditions of the existing Lease, for an
additional one (1) year term with a new expiration date of August 31, 2002.

         All other conditions of the Lease shall remain the same. Please
acknowledge receipt of this notice by signing and returning a copy of this
letter.

TENANT:  COGENT COMMUNICATIONS, INC

                  /s/
--------------------------------------------
Thaddeus G. Weed
Title: VP, Controller

LANDLORD:  6715 KENILWORTH AVENUE PARTNERSHIP

                  /s/
--------------------------------------------
Dave Schaeffer
Title: General Partner

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