Exhibit 10.5.1
  AMENDMENT OF SOLICITATION/MODIFICATION OF CONTRACT
    
    
    1. Contract 
ID Code
    
    

Page of Pages1
    
    3
 2. Amendment/Modification No.
0006
    
    
    3. Effective Date 

See Block 16C
    
    
    4. Requisition/Purchase Req. No.
NTIA9000-0-09914
    
    
    5. Project No. (if applicable)
 6. Issued By            
                                  Code F6001201
DOC/NOAA/AGO
STAFF OFFICE & EXTERNAL CLIENTS, AD
1305 EAST WEST HIGHWAY, RM 7601
SILVER SPRING, MD 20910
JAMES A WEBB 301-713-0838 102
    
    
    7. Administered By (if other than Item 6)               Code
SEE BLOCK 6
 8. Name and Address of Contractor (No., Street, County, and Zip Code)
    
    (X)
    

    9A. Amendment of Solicitation No.NEUSTAR, INC.
46000 CENTER OAK PLAZA
STERLING VA 20166-6593
    
    
    Vendor ID: 00000190
DUNS: 112403295
CAGE: 3DXC3
    
    
    
    
    
    9B. Date (See Item 11)X
    
    
    10A. Modification of Contract/Order No. 
DG1335-08-CN-000210B. Date (See Item 13) 
Oct 18, 2007Code
    
    
    Facility Code
 
 o  ̈  ̈
 if required
 
 (x)


    

A.
This change order is issued pursuant to: (Specify authority)
The changes set forth in item 14 are made in the Contract Order No.
in item 10A.B.
The above numbered Contract/Order is modified to reflect the
administrative changes (such as changes in paying office,
appropriation date, etc.)Set
fourth Item 14, pursuant to the authority of FAR 43.103(b)x

    
    

C.
This supplemental agreement is entered into pursuant to authority
of:By
Mutual Agreement of both parties FAR 43.103(a) (3)D. Other (Specify type of
modification and authority)
 E. IMPORTANT: Contractor
    
    

þ is not,       o Is required to sign this document and return ___ copies to the issuing office.
 Organized by UCF section headings, including solicitation/contract subject matter where feasible.
     15A. Name and Title of Signer (Type or Print)
    
    
    16A. Name and title of Contracting Officer (Type or Print)Bradley D. Smith
Vice President, Finance & Corporate Controller
    
    
    TERRI COLEY
                    
                   301-713-0838 x139
TEAM LEADER, ECAD
terri.coley@noaa.gov
 15B. Contractor/Offeror
    
    
    15C. Date Signed
    
    
    16B. United States of America
    
    
    16C. Date Signed/s/ Bradley D. Smith
    
    
    June 12, 2009
    
    
    /s/ Terri Colley
    
    
    6/16/09(Signature of person authorized to sign)
    
    
    
    
    
    (Signature of Contracting Officer)
 NSN 7540-01-152-8070
PREVIOUS EDITIONS UNUSABLE
    
    30-105
    
    STANDARD FORM 30 (REV. 10-83)
Prescribed by GSA FAR (48 CFR) 53.243




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SF30 Continuation of Block Narrative
    
    
    Page 2 of 3
 3.)
    
    [* * *]4.)
    
    [* * *]5.)
    
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SCHEDULE
 Item No.
    
    Supplies/Services
    
    Quantity
    
    Unit
    
    Unit Price
    
    Amount0001
    
    
    BASE PERIODPerform the services required by the SOW

Period of Performance: Base 3 year period plus 2

option years (5 years), beginning on October 26,
2007.
    
    
    1
    
    
    EA
    
    
    0.00
    
    
    
    0.00