DNS Client Failure Manager Preserves Cache Entries

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Solution Overview

Problem

DNS clients face communication disruptions due to network connection failures and DNS server failures, which prevent DNS entries from being updated in local caches, leading to halted communication processes.

Innovation Solution

A DNS client with a failure manager that preserves DNS entries in the local cache and resets the TTL timer in case of network or DNS server failures, and flushes entries upon permanent failure conditions, allowing continued communication by maintaining valid DNS information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If the DNS client updates DNS entries in the local cache from the DNS server, then the DNS information accuracy is improved, but the communication process is halted when the DNS server is unreachable or returns an error

Engineering Contradiction:

ImproveDNS information accuracyVSAvoidcommunication continuity

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The system performs preliminary actions by checking the reachability of the DNS server before attempting to update DNS entries. When the server is unreachable or returns an error, the system proactively preserves the existing DNS entries in the local cache rather than allowing the communication process to halt, thus maintaining communication continuity while preserving information accuracy within the constraints of the failure condition

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system converts the harmful effect of DNS server failures (unreachable server or error responses) into a beneficial outcome by implementing error handling that preserves DNS entries in the local cache. Instead of treating server unavailability as a reason to halt communication, the system uses it as a trigger to maintain existing valid DNS information, thereby transforming a communication-blocking scenario into a communication-maintaining scenario

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Loss of information

If the DNS client waits for DNS server response to update entries, then the DNS information freshness is improved, but the communication process is disrupted during network failures

Engineering Contradiction:

ImproveDNS information freshnessVSAvoidcommunication efficiency

Core Design Contradiction:

Loss of informationVSProductivity

Solution Approach 1:

The system performs preliminary checks to determine whether the DNS server is reachable before initiating the DNS update process. When the server is unreachable, the system proactively preserves existing DNS entries in the local cache, avoiding communication disruptions and maintaining productivity while accepting that information freshness cannot be updated under failure conditions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements beforehand cushioning by preparing error handling mechanisms in advance that preserve DNS entries when server failures occur. This cushioning approach ensures that communication processes are not disrupted by network failures or server errors, as the system has already established fallback behavior to maintain existing DNS information in the local cache

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS8799718B2Failure system for domain name system client

Publication Date: 2014.08.05 VERIZON PATENT & LICENSING INC

AI summary

A method performed by a domain name service client includes storing DNS entries in a local cache; sending a DNS query to another device to obtain an update to one of the DNS entries; determining whether a DNS response is received; and resetting a time-to-live (TTL) timer associated with the one of the DNS entries when the DNS response is not received.