Prepared by MERRILL CORPORATION www.edgaradvantage.com QuickLinks -- Click here to rapidly navigate through this document

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

AMENDMENT NO. 2 TO
SCHEDULE 13D
(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED
PURSUANT TO RULE 13d-1(a) AND AMENDMENTS THERETO
FILED PURSUANT TO RULE 13d-2(a)

 
INTERNAP NETWORK SERVICES CORPORATION
(Name of Issuer)
 
Common Stock, $0.001 Per Share

(Title of Class of Securities)
 
45885A 10 2

(CUSIP Number)
 
Robert J. Lunday, Jr.
InterNAP Network Services Corporation
Two Union Square, 601 Union Street
Seattle, WA 98101
(206) 441-8800

(Name, Address and Telephone Number of Person Authorized
to Receive Notices and Communications)
 
November 14, 2000

(Date of Event which Requires Filing of this Statement)

    If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box  / /.

    Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7(b) for other parties to whom copies are to be sent.

    *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

    The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).



CUSIP No.  45885A 10 2   Amendment No. 2 to 13D   Page 2 of 4 Pages


 
1.
 
 
 
Names of Reporting Persons.
I.R.S. Identification Nos. of above persons (entities only).
 
 
 
 
 
Robert J. Lunday, Jr.

 
2.
 
 
 
Check the Appropriate Box if a Member of a Group (See Instructions)
    (a)  / /
 
 
 
 
 
(b)  / /

 
3.
 
 
 
SEC Use Only

 
4.
 
 
 
Source of Funds  
OO

 
5.
 
 
 
Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  / /

 
6.
 
 
 
Citizenship or Place of Organization  
U.S.A.

Number of   7.   Sole Voting Power  5,168,772
Shares  
Beneficially   8.   Shared Voting Power  0
Owned by Each  
Reporting   9.   Sole Dispositive Power  5,168,722
Person With  
    10.   Shared Dispositive Power  0

11.   Aggregate Amount Beneficially Owned by Each Reporting Person
5,168,722

 
12.
 
 
 
Check if the Aggregate Amount in Row (11) Excludes Certain Shares  / /

 
13.
 
 
 
Percent of Class Represented by Amount in Row (11)  
3.5%

 
14.
 
 
 
Type of Reporting Person
IN
     

2


Item 1. Security and Issuer

    This statement on Schedule 13D relates to the Common Stock, $.001 par value per share (the "Common Stock"), of InterNAP Network Services Corporation, a Washington corporation ("InterNAP"). The principal executive offices of InterNAP are located at 601 Union Street, Suite 1000, Seattle, WA 98101. The Common Stock is quoted on the Nasdaq National Market under the symbol "INAP."

Item 2. Identity and Background

Item 3. Source and Amount of Funds or Other Consideration

    Not applicable.

Item 4. Purpose of Transaction

3


Item 5. Interest in Securities of the Issuer



    Aggregate Number:   5,168,722  
    Percentage of Class:   3.5 %

    Sole Voting Power   5,168,722
    Shared Voting Power   0
    Sole Dispositive Power   5,168,722
    Shared Dispositive Power   0



Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.

    Other than as described in Item 5 above, to the Reporting Person's knowledge, there are no contracts, arrangements, understandings or relationships (legal or otherwise) among the persons named in Item 2 and between such persons and any person with respect to any securities of InterNAP, including but not limited to transfer or voting of any of the securities, finder's fees, joint ventures, loan or option arrangements, puts or calls, guarantees of profits, division of profits or loss, or the giving or withholding of proxies.

Item 7. Material to be Filed as Exhibits

    None


SIGNATURE

    After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: November 28, 2000   REPORTING PERSON:
 
 
 
 
 
 
    /s/ ROBERT J. LUNDAY, JR.   
Robert J. Lunday, Jr.

4




QuickLinks

SIGNATURE