Patent ID: 8103915

Claim:
A method comprising: storing, by a domain name system (DNS) client device, DNS entries in a local cache; sending, by the DNS client device, a DNS query to another device to obtain an update to one of the DNS entries; receiving a DNS response; inspecting a response code value included in the DNS response; determining an error category of the response code value; deleting the one of the DNS entries, when in response to the determining, the error category indicates that the one of the DNS entries is to be deleted, and saving the one of the DNS entries and resetting a time-to-live (TTL) timer associated with the one of the DNS entries, when in response to the determining, the error category indicates that the one of the DNS entries is to be saved and the time-to-live (TTL) timer is to be reset, wherein when determining whether the error category, the method further comprises: determining whether the response code value corresponds to a temporary failure or a permanent failure.