US Patent 7970765 Network device for providing integrated DNS caching services

This disclosure describes domain name system (DNS) caching techniques for providing integrated DNS caching services to multiple customers. For example, a virtual private network (VPN) device provides integrated DNS caching services to multiple customers even though each customer has a different corresponding VPN and may be serviced by a different DNS server. The VPN network device accesses the multiple, different DNS servers to retrieve correct IP addresses for the different customer VPNs, and internally stores the IP addresses in an integrated DNS cache in a manner that allows the IP addresses to be uniquely retrieved based on combinations of customer VPN identifiers and hostnames.