This facility can provide a mechanism for security and privacy management by logical or physical separation of DNS information for network-internal access (within an administrative domain, e.g., company) and access from an insecure, public network (e.g. the Internet).
Implementation of split-horizon DNS can be accomplished with hardware-based separation or by software solutions. Hardware-based implementations run distinct DNS server devices for the desired access granularity within the networks involved. Software solutions use either multiple DNS server processes on the same hardware or special server software with the built-in capability of discriminating access to DNS zone records. The latter is a common feature of many server software implementations of the DNS protocol (cf. Comparison of DNS server software) and is sometimes the implied meaning of the term split-horizon DNS, since all other forms of implementation can be achieved with any DNS server software.
US Patent Issued to Oracle America on July 26 for "Distributed Denial of Service Congestion Recovery Using Split Horizon Dns" (California Inventor)
Jul 30, 2011; ALEXANDRIA, Va., July 30 -- United States Patent no. 7,987,255, issued on July 26, was assigned to Oracle America Inc. (Redwood...