Proxy DNS Server Caching for Service Continuity
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Solution Overview
Problem
Current DNS query management systems are vulnerable to denial-of-service (DoS) and distributed denial-of-service (DDoS) attacks, and they inefficiently handle recursive queries, leading to resource and bandwidth wastage, especially when authoritative DNS servers are down or inaccessible.
Innovation Solution
Implementing a proxy DNS server that caches DNS responses based on Time to Live (TTL) values and acts as an intermediary between requesting devices and DNS nameservers, mitigating attacks by processing queries and providing cached responses instead of recursively querying authoritative servers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a proxy DNS server caches DNS responses and provides cached answers, then service continuity is maintained when authoritative servers are down, but DNS record freshness may be compromised
Solution Approach 1:
The proxy DNS server performs preliminary actions by caching DNS responses before authoritative servers become unavailable. It stores resource records with their TTL values and continues to serve cached responses during outages, ensuring service continuity while maintaining record validity within the cached TTL period
Solution Approach 2:
The proxy DNS server prepares compensatory measures in advance by maintaining a cache of DNS resource records. When authoritative servers go down, the cached records act as a cushion that allows the system to continue operating without immediate failure, bridging the gap until servers are restored
2Object-affected harmful factors
If a proxy DNS server acts as an intermediary and processes queries locally, then security is enhanced by protecting authoritative servers from attacks, but query processing complexity increases
Solution Approach 1:
The proxy DNS server functions as an intermediary between client devices and authoritative DNS servers. It receives and processes DNS queries locally, using its cached resource records to answer questions without always contacting authoritative servers, thereby protecting them from direct exposure to attack traffic while managing query processing
Solution Approach 2:
The proxy DNS server enables self-service by autonomously processing DNS queries using its locally cached resource records. It can independently answer queries for cached domains without requiring real-time communication with authoritative servers, reducing their exposure to harmful traffic while maintaining efficient query resolution
3Measurement precision
If recursive DNS queries are performed to authoritative servers, then accurate DNS resolution is achieved, but resource and bandwidth wastage occurs when servers are inaccessible
Solution Approach 1:
The proxy DNS server performs preliminary DNS resolution by obtaining resource records from authoritative servers before they become inaccessible and storing them in cache. When servers are later unavailable, it serves these pre-obtained records, avoiding wasted recursive query attempts and conserving network bandwidth and computational resources
Solution Approach 2:
The proxy DNS server applies partial action by performing recursive queries only when necessary - specifically when a requested resource record is not already in cache or when the cached record has expired. This selective approach avoids excessive querying when cached records can satisfy requests, reducing resource and bandwidth consumption
Data Source
AI summary
A proxy server for an authoritative nameserver of a domain receives a query from a requesting device directed to the authoritative nameserver for a resource record associated with the domain. The proxy server receives the query from the requesting device instead of the authoritative nameserver for the domain. The proxy server determines that a cached record for the queried resource record is in cache available to the proxy server but is expired, and queries the authoritative nameserver of the domain for the resource record. In response to determining that the authoritative nameserver of the domain failed to respond with the queried resource record, the proxy server accesses, in the cache available to the proxy server, the cached record for the resource record that is expired, and transmits the expired cached record for the resource record to the requesting device.