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                                                                   EXHIBIT 10.10


                             The New D&B Corporation
                              One Diamond Hill Road
                          Murray Hill, New Jersey 07974




                                     September __, 2000

Steven B. Witznitzer, Esq.
R.H. Donnelley Corporation
One Manhattanville Road
Purchase, New York  10577

Dear Sir:

           Reference is made to the Distribution Agreement (the "1998
Distribution Agreement"), dated as of June 30, 1998, between The Dun &
Bradstreet Corporation, now known as "R.H. Donnelley Corporation" ("Historical
D&B"), and The New Dun & Bradstreet Corporation, now known as "The Dun &
Bradstreet Corporation" ("D&B"). D&B has announced its intention to separate
into two separate companies through a distribution (the "2000 Distribution") to
its stockholders of all of the shares of common stock of its subsidiary The New
D&B Corporation ("New D&B"). In Section 8.9(b) of the 1998 Distribution
Agreement, D&B agreed not to make a distribution such as the 2000 Distribution
unless it caused the distributed entity to undertake to Historical D&B to be
jointly and severally liable for all D&B Liabilities (as defined in the 1998
Distribution Agreement). Therefore, in accordance with Section 8.9(b) of the
1998 Distribution Agreement and intending to be legally bound hereby, from and
after the effective time of the 2000 Distribution, New D&B undertakes to
Historical D&B to be jointly and severally liable with D&B for all D&B
Liabilities under the 1998 Distribution Agreement.

                                         Very truly yours,

                                         THE NEW D&B CORPORATION


                                         By:___________________________
                                             Name:
                                             Title: