Exhibit 10.5.3

                                                             
AMENDMENT OF SOLICITATION/MODIFICATION OF CONTRACT
    1. CONTRACT ID CODE     Page
 
                                                    1 of 1                      
                2. Amendment/Modification No.     3. Effective Date     4.
Requisition/Purchase Req. No.     5. Project No. (If applicable)     0017    
    Aug 24, 2006         NT1A911-6-0279ML                                      
                                 
6. Issued By                                              Code
      F6001201       7. Administered By (If other than Item 6)     Code        
 
 
                                                       
DOC/NOAA/AGO
              SEE BLOCK 6                                        
STAFF OFFICE & EXTERNAL CLIENTS, AD
                                                           
1305 EAST WEST HIGHWAY, RM 7601
                                                           
SILVER SPRING, MD 20910
                                                           
DIANE R. TRICE 301-713-0838 X 102

                                                                               
                 

                        8. Name and Address of Contractor (No., Street, County
and Zip Code)     (X)     9A. Amendment of Solicitation No.                    
   
NEUSTAR, INC.
        Vendor ID 00000190           9B. Date (See Item 11)                    
   
46000 CENTER OAK PLAZA
STERLING, VA 20166
        DUNS: 112403295     X     10A. Modification of Contract/Order No.
SB1335-02-W-0175                        
 
        CAGE: 3DXC3           10B. Date (See Item 13) Oct. 26, 2001            
       
Code
    Facility Code                                     11. THIS ITEM ONLY APPLIES
TO AMENDMENTS OF SOLICITATIONS
                   

     
o
  The above numbered solicitation is amended as set forth in Item 14. The hour
and date specified for receipt of Offers o is extended, o is not extended.
 
   
 
  Offers must acknowledge receipt of this amendment prior to the hour and date
specified in the solicitation or as amended, by one of the following methods:
 
   
 
 
(a) By completing Items 8 and 15, and returning ___ copies of the amendment;
(b) By acknowledging receipt of this amendment on each copy of the offer
submitted; or (c) By separate letter or telegram which includes a reference to
the solicitation and amendment numbers. FAILURE OF YOUR ACKNOWLEDGMENT TO BE
RECEIVED AT THE PLACE DESIGNATED FOR THE RECEIPT OF OFFERS PRIOR TO THE HOUR AND
DATE SPECIFIED MAY RESULT IN REJECTION OF YOUR OFFER. If by virtue of this
amendment you desire to change an offer already submitted, such change may be
made by telegram or letter, provided each telegram or letter makes reference to
the solicitation and this amendment, and is received prior to the opening hour
and date specified.

        12. Accounting and Appropriation Data (If required)
          $ US          0.00   13. THIS ITEM ONLY APPLIES TO MODIFICATIONS OF
CONTRACT/ORDERS.
IT MODIFIES THE CONTRACT/ORDER NO. AS DESCRIBED IN ITEM 14.

               
 
             
(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:
FAR 52.243-1 “Changes”, and Mutual Agreement of the Parties
       
 
  D.
Other (Specify type of modification and authority)

       

E. IMPORTANT: Contractor x is not, o is required to sign this document and
return ___ copies to the issuing office.
 
14. Description of Amendment/Modification (Organized by UCF section headings,
including solicitation/contract subject matter where feasible.)
Modification No. 0017 is being issued to accomplish the following:
1. To approve the .US Locality Domain Name Registration Terms and Conditions
dated July 19, 2006 and the .US Service Enhancement Agreement dated August 15,
2006. The agreements are effective with the fully executed date of this
modification.
2. To amend the deadlines set forth in Modification No. 15 as follows:
a) Launch of first second level domain and related services by August 24, 2006.
b) Launch of .us directory search capability by August 24th, 2006.
 
Except as provided herein, all terms and conditions of the document referenced
in Item 9A or 10A, as heretofore changed, remains unchanged and in full force
and effect.

                                                    15A. Name and Title of
Signer (Type or Print)       16A. Name and title of Contracting Officer (Type or
Print)           Steven Boyce, VP & Controller         CATHERINE E. HOLLAND    
301-713-0838 X139               Contracting Officer                          
catherine.holland@noaa.gov                                
15B. Contractor/Offeror
    15C. Date Signed     16B.   United States of America         16C. Date
Signed           /s/ Steven Boyce     Aug. 25, 2006     /s/ Catherine E. Holland
        August 24, 2006                                       (Signature of
person authorized to sign)           (Signature of Contracting Officer)
             

NSN 7640-01-152-8070
PREVIOUS EDITIONS UNUSABLE             30-105   STANDARD FORM 30 (REV. 10-83)
Prescribed by GSA FAR (48 CFR) 53.243

--------------------------------------------------------------------------------

 

                                                             
AMENDMENT OF SOLICITATION/MODIFICATION OF CONTRACT
    1. CONTRACT ID CODE     Page
 
                                                      1 of 1                    
                  2. AMENDMENT/MODIFICATION NO.     3. EFFECTIVE DATE     4.
REQUISITION/PURCHASE REQ. NO.     5. PROJECT NO. (If applicable)      0018      
   Oct 20, 2006         NTIA911-7-029IML                                        
                         
6. ISSUED BY                               CODE
    F6001201       7. ADMINISTERED BY (If other than Item 6)
    SEE BLOCK 6     CODE          
 
                                                       
 
                                                           
DOC/NOAA/AGO
                                                           
STAFF OFFICE & EXTERNAL CLIENTS, AD
                                                           
1305 EAST WEST HIGHWAY, RM 7601
                                                           
SILVER SPRING, MD 20910
                                                            DIANE R. TRICE
301-713-0838 x102                                    

11                        8. NAME AND ADDRESS OF CONTRACTOR (No., street,
county, and Zip Code)     (X)     9A. AMENDMENT OF SOLICITATION NO.            
               
NEUSTAR, INC.
    Vendor ID: 00000190           9B. DATE (SEE ITEM 11)                        
   
46000 CENTER OAK PLAZA
STERLING, VA 201666593
    DUNS: 112403295               10A. MODIFICATION OF CONTRACT/ORDER
NO. SB1335-02-W-0175                            
 
    CAGE: 3DXC3               (X)     10B. DATE (SEE ITEM 13)
Oct 26, 2001                            
CODE*
    FACILITY CODE                                         11. THIS ITEM ONLY
APPLIES TO AMENDMENTS OF SOLICITATIONS
                   

      c   The above numbered solicitation is amended as set forth in Item 14.
The hour and date specified for receipt of Offers c is extended, c is not
extended.
 
   
 
  Offers must acknowledge receipt of this amendment prior to the hour and date
specified in the solicitation or as amended, by one of the following methods:
 
   
 
 
(a) By completing Items 8 and 15, and returning ___ copies of the amendment;
(b) By acknowledging receipt of this amendment on each copy of the offer
submitted; or (c) By separate letter or telegram which includes a reference to
the solicitation and amendment numbers. FAILURE OF YOUR ACKNOWLEDGMENT TO BE
RECEIVED AT THE PLACE DESIGNATED FOR THE RECEIPT OF OFFERS PRIOR TO THE HOUR AND
DATE SPECIFIED MAY RESULT IN REJECTION OF YOUR OFFER. If by virtue of this
amendment you desire to change an offer already submitted, such change may be
made by telegram or letter, provided each telegram or letter makes reference to
the solicitation and this amendment, and is received prior to the opening hour
and date specified.

        12. ACCOUNTING AND APPROPRIATION DATA (If required)
       6107911001100008000000000000000000000000025220000000000 $ US       0.00  
13. THIS ITEM APPLIES ONLY TO MODIFICATIONS OF CONTRACT/ORDERS.
IT MODIFIES THE CONTRACT/ORDER NO. AS DESCRIBED IN ITEM 14.

               
(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
IN ITEM 14, PURSUANT TO THE AUTHORITY OF FAR 43.103(b).
       
 
   
C. THIS SUPPLEMENTAL AGREEMENT IS ENTERED INTO PURSUANT TO AUTHORITY OF:
       
X
    D. OTHER (Specify type of modification and authority)
 
    FAR 52217-9 Option to Extend the Term of the Contract        

      E. IMPORTANT: Contractor x is not, o is required to sign this document and
return     copies to the issuing office.   14. DESCRIPTION OF
AMENDMENT/MODIFICATION (Organized by UCF section headings, including
solicitation/contract subject matter where feasible.)

The purpose of this modification is to exercise the second One-Year Option to
extend the contract for 365 days. The period of performance is: October 26, 2006
through October 25, 2007.

         

                                   
 
                                Except as provided herein, all terms and
conditions of the document referenced in Item 9A or 10A, as heretofore changed,
remains unchanged and in full force and effect.                              
15A.
    NAME AND TITLE OF SIGNER (Type or print)            16A.   NAME AND TITLE OF
CONTRACTING OFFICER (Type of print)
 
                    GARY RICE     301-713-0838 x190    
 
                    Contracting Officer          
 
                    gary.rice@noaa.gov          
 
                                                             
15B.
    CONTRACTOR/OFFEROR     15C. DATE SIGNED     16B.   United States of America
    16C. DATE SIGNED
Oct 20, 2006    
 
                                                                 
 
    (Signature of person authorized to sign)           BY         /s/ Gary Rice
                                           
 
                                (Signature of Contracting Officer)          

         
NSN 7540-01-152-8070
  30-105 STANDARD FORM 30 (REV. 10-83)
PREVIOUS EDITIONS
    Prescribed by GSA FAR (48 CFR)
UNUSABLE
    53.243