A first computing device receives a first token with a first request for data from a second computing device located at a first network address, the first token being associated with a second network addresses previously associated with the second computing device during previous communications with the first computing device. The first computing device determines that the first token is not associated with the first network address, and generates a second token for the computing device. The second token is associated with the first network address and the second network address. The first computing device then provides the second token to the computing device for use in establishing future network communications from the first network address and from the second network address.