This excerpt taken from the VRSN 10-K filed Jul 12, 2007.
7. METHOD OF ACCESS
VNDS reserves the right, with the approval of ICANN, to change the method of access to the Data at any time. You also agree that, in the event of significant degradation of system processing or other emergency, VNDS may, in its sole discretion, temporarily suspend access under this Agreement in order to minimize threats to the operational stability and security of the Internet.