Recursive DNS Nameserver Cached Record Handling
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Solution Overview
Problem
Current DNS systems face inefficiencies in domain name resolution, particularly when authoritative nameservers are unavailable, leading to network traffic increases and performance issues due to the need for recursive nameservers to repeatedly check for fresh data, even if cached records with expired TTLs can still provide meaningful responses.
Innovation Solution
Recursive DNS nameservers are configured to utilize local caches with expired TTL records, generating responses from these records when authoritative servers are unreachable, and modifying caching techniques to maintain records with expired TTLs, while also considering user-defined preferences for handling expired data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If recursive nameservers repeatedly check for fresh data from authoritative servers, then data freshness is improved, but network traffic increases and performance deteriorates
Solution Approach 1:
The patent changes the parameter of TTL (time-to-live) handling by allowing recursive nameservers to return cached records even when TTL has expired, under specific conditions. This parameter change enables the system to maintain data freshness through alternative means (direct client requests to authoritative servers) while improving performance by utilizing cached data.
Solution Approach 2:
The patent introduces an intermediary mechanism where the recursive nameserver acts as a mediator between client requests and authoritative servers. When authoritative servers are unavailable or unresponsive, the recursive nameserver uses cached records as an intermediary to fulfill client requests, reducing the need for direct queries to authoritative servers.
2Measurement precision
If recursive nameservers wait for authoritative servers to become available, then data accuracy is improved, but service continuity deteriorates
Solution Approach 1:
The patent applies beforehand cushioning by maintaining cached records with expired TTLs in the recursive nameserver's cache. When authoritative servers become unavailable, these pre-cached records provide a cushion that allows the system to continue serving clients without immediate service interruption. The system can later update records when authoritative servers become available again.
Solution Approach 2:
The patent introduces dynamic behavior where the recursive nameserver adapts its response based on the availability status of authoritative servers. The system dynamically switches between serving cached records and querying authoritative servers, and can dynamically update cache entries when authoritative servers become available, providing flexible service continuity.
3Reliability
If recursive nameservers return cached records with expired TTLs, then service availability is improved, but data freshness deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the handling of cached records based on specific conditions. Not all cached records with expired TTLs are treated the same way - the system selectively returns cached records only when authoritative servers are unavailable or unresponsive, while still attempting to obtain fresh data when possible. This localized approach maintains service availability without universally sacrificing data freshness.
Solution Approach 2:
The patent implements feedback mechanisms where the recursive nameserver monitors the availability and responsiveness of authoritative servers. Based on this feedback, the system adjusts its behavior - returning cached records when authoritative servers are unavailable, but attempting to refresh records when they are available. This feedback loop balances service availability with data freshness.
Data Source
AI summary
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.