Patent attributes
A recursive DNS nameserver system and related domain name resolution techniques are disclosed. The DNS nameservers utilize a local cache having previously retrieved domain name resolution to avoid recursive resolution processes and the attendant DNS requests. If a matching record is found with a valid (not expired) TTL field, the nameserver returns the cached domain name information to the client. If the TTL for the record in the cache has expired and the nameserver is unable to resolve the domain name information using DNS requests to authoritative servers, the recursive DNS nameserver returns to the cache and accesses the resource record having an expired TTL. The nameserver generates a DNS response to the client device that includes the domain name information from the cached resource record. In various embodiments, subscriber information is utilized to resolve the requested domain name information in accordance with user-defined preferences.
