GUARANTEE AGREEMENT

          GUARANTEE AGREEMENT, dated as of February 6, 2007 (as the same may be amended, supplemented or otherwise modified from time to time, this Agreement), made by each of the signatories hereto (together with any other entity that may become a party hereto as provided herein, the Guarantors), in favor of JPMorgan Chase Bank, N.A., as administrative agent (in such capacity, the Administrative Agent) for the banks and other financial institutions or entities (the Lenders) from time to time parties to the Credit Agreement, dated as of February 6, 2007 (as amended, supplemented or otherwise modified from time to time, the Credit Agreement), among Neustar, Inc. (the Borrower), the Lenders and the Administrative Agent for the ratable benefit of the Lenders and their respective successors, indorsees, transferees and assigns.

W I T N E S S E T H:

          WHEREAS, pursuant to the Credit Agreement, the Lenders have severally agreed to make extensions of credit to the Borrower upon the terms and subject to the conditions set forth therein;

          WHEREAS, the Borrower is a member of an affiliated group of companies that includes each Guarantor;

          WHEREAS, the proceeds of the extensions of credit under the Credit Agreement have been and will be used in part to enable the Borrower to make valuable transfers to one or more of the Guarantors in connection with the operation of their respective businesses;

          WHEREAS, the Borrower and the Guarantors are engaged in related businesses, and each Guarantor will derive substantial direct and indirect benefit from the making of the extensions of credit under the Credit Agreement; and

          WHEREAS, it is a condition precedent to the obligation of the Lenders to make their respective extensions of credit to the Borrower under the Credit Agreement that the Guarantors shall have executed and delivered this Agreement to the Administrative Agent for the ratable benefit of the Lenders;

          NOW, THEREFORE, in consideration of the premises and the Administrative Agent and the Lenders having entered into the Credit Agreement and to induce the Lenders to make their respective further extensions of credit to the Borrower thereunder, each Guarantor hereby agrees with the Administrative Agent, for the ratable benefit of the Lenders, as follows:

SECTION 1. DEFINED TERMS

     1.1 Definitions. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement.

     1.2 Other Definitional Provisions. (a) The words hereof, herein, hereto and hereunder and words of similar import when used in this Agreement shall refer to this Agreement as a whole and not to any particular provision of this Agreement, and Section and Schedule references are to this Agreement unless otherwise specified.

     (b) The meanings given to terms defined herein shall be equally applicable to both the singular and plural forms of such terms.

SECTION 2. GUARANTEE

     2.1 Guarantee. (a) Each of the Guarantors hereby, jointly and severally, unconditionally and irrevocably, guarantees to the Administrative Agent, for the ratable benefit of the Lenders and their respective successors, indorsees, transferees and assigns, the prompt and complete payment and performance by the Borrower when due (whether at the stated maturity, by acceleration or otherwise) of the Obligations. The guarantee provided under this Agreement is a guarantee of payment and not of collection.

     (b) Anything herein or in any other Loan Document to the contrary notwithstanding, the maximum liability of each Guarantor hereunder and under the other Loan Documents shall in no event exceed the amount which can be guaranteed by such Guarantor under applicable federal and state laws relating to the insolvency of debtors without rendering its obligations hereunder subject to avoidance as a fraudulent transfer or conveyance under Section 548 of the Bankruptcy Code (Title 11, United States Code) or any comparable provision of any Federal or state law (in each case, after giving effect to the right of contribution established in Section 2.2).