# US 11,122,138 B2 · Enhanced domain name system response caching > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,122,138 B2 - Document ID: US11122138B2 - Status: Granted - Kind: B2 - Application number: 17/012,520 - Filed: 2020-09-04 - Published: 2020-12-24 - Granted: 2021-09-14 - Earliest claimed: 2019-03-08 - Assignees: Charter Communications Operating, LLC - Applicants: Charter Communications Operating, LLC - Inventors: Ashutosh Kumar Sinha; Robert Dianda - Web page: https://patentgrep.com/patent/US11122138B2 ## CPC - H04L 61/58: Caching of addresses or names - G06F 16/24552: {Database cache management} - H04L 61/4511: using domain name system [DNS] - H04L 67/568: Storing data temporarily at an intermediate stage, e.g. caching - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract Methods and systems for enhanced domain name system (DNS) response caching are described. An enhanced DNS response caching method includes receiving a connection request for a fully qualified domain name (FQDN). A DNS client checks a local cache for a cached resolved domain name corresponding to the FQDN and sends 3300 a query to obtain or refresh the cached resolved domain name if a Time to Live parameter is expired or about to expire. In response to receiving a negative response or no response for the query, the DNS client determines whether an enhanced DNS response caching parameter is enabled. If the enhanced DNS response caching parameter is enabled, the DNS client sends an expired cached resolved domain name to process the connection request. ## Claims ### Claim 1 A method for enhanced domain name system (DNS) response caching, the method comprising: querying a cache for a cached resolved domain name associated with a connection request; using a request type to set enhanced DNS response caching parameter enablement in response to non-refreshment of a matching cached resolved domain name; and processing the connection request by sending an expired matching cached resolved domain name for an enabled enhanced DNS response caching parameter. ### Claim 2 (depends on 1) The method of claim 1, the method further comprising: storing cached resolved domain names in the cache for time to live values specified in resolved domain name responses. ### Claim 3 (depends on 2) The method of claim 2, the method further comprising: maintaining, until a positive response is received, expired cached resolved domain names when the enhanced DNS response caching parameter is enabled. ### Claim 4 (depends on 2) The method of claim 2, wherein the cached resolved domain names are refreshed when time to live values expire or are about to expire. ### Claim 5 (depends on 1) The method of claim 1, wherein determination of enhanced DNS response caching parameter enablement uses domain name type. ### Claim 6 (depends on 1) The method of claim 1, wherein determination of enhanced DNS response caching parameter enablement uses type of DNS client device. ### Claim 7 (depends on 1) The method of claim 1, wherein determination of enhanced DNS response caching parameter enablement uses application type of domain name. ### Claim 8 (depends on 1) The method of claim 1, wherein a default setting for the enhanced DNS response caching parameter is enabled for some application types, some DNS client device types, some types of requesting devices, some domain name types, or combinations thereof. ### Claim 9 A method for processing requests with domain name system (DNS) response failures, the method comprising: checking for a cached resolved Internet Protocol (IP) address corresponding to a domain name in a request; enabling, based on a DNS client device type, use of an expired identified cached resolved IP address when a query for an identified cached resolved IP address is one of unresponsive or negative; and processing the request by sending the expired identified cached resolved IP address. ### Claim 10 (depends on 9) The method of claim 9, the method further comprising: storing cached resolved IP addresses in the cache for time to live values specified in resolved IP responses. ### Claim 11 (depends on 10) The method of claim 10, the method further comprising: not flushing, until a positive response is received, expired cached resolved IP addresses when use is enabled of the expired identified cached resolved IP address. ### Claim 12 (depends on 10) The method of claim 10, the method further comprising: renewing the cached resolved IP addresses relative to time to live expiry. ### Claim 13 (depends on 9) The method of claim 9, wherein determination of the type uses the requested domain name. ### Claim 14 (depends on 10) The method of claim 10, wherein determination of the type uses application associated with the requested FQDN. ### Claim 15 A domain name system (DNS) device comprising: a client configured to issue DNS queries to DNS servers; a memory configured to store: resolved Internet Protocol (IP) addresses; and an enablement flag, wherein setting an enablement flag allows use of expired stored resolved IP addresses; and a processor in cooperation with the DNS client and memory configured to: determine a request device type for a request when a response failure occurs for a query related to an identified stored resolved IP address; and process the request by sending an expired identified stored resolved IP address when an enablement flag is set based on the request device type. ### Claim 16 (depends on 15) The DNS device of claim 15, the processor further configured to: not flush, until a positive response is received, expired stored resolved IP addresses when the enablement flag is set. ### Claim 17 (depends on 15) The DNS device of claim 15, the memory configured to store time to live values associated with the stored resolved IP addresses, and the processor further configured to: refresh stored resolved IP addresses when time to live values expire or are about to expire. ### Claim 18 (depends on 15) The DNS device of claim 15, the memory configured to store resolved IP addresses for time to live values specified in resolved IP address responses. ### Claim 19 (depends on 15) The DNS device of claim 15, wherein a default setting for the enablement flag is enabled for some application types, some client device types, some request device types, some domain name types, or combinations thereof. ### Claim 20 (depends on 15) The DNS device of claim 15, the processor further configured to: set the enablement flag based on the request device type.