DNS Query Detection for Gateway Stability
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Solution Overview
Problem
Internet gateways with functional limitations can incorrectly handle DNS queries, leading to crashes and disruption of internet access for multiple devices sharing a single connection, necessitating a method to detect such limitations without causing the DNS server to fail.
Innovation Solution
A system sends a specially constructed exploratory query to the DNS server to detect functional limitations without causing it to crash, using a 'reverse-lookup' DNS query for a sub-domain of the loopback address, and takes remedial actions if an incorrect response is received, such as disabling features that may crash the server.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a standard DNS query is sent to test the DNS server, then the query structure is simple, but it may cause the DNS server to crash if the server has functional limitations
Solution Approach 1:
The system performs preliminary actions by sending a specially constructed exploratory query before normal DNS operations. This query is designed to detect functional limitations in advance, allowing the system to take preventive measures (such as disabling problematic features) before crashes occur during regular DNS resolution
Solution Approach 2:
The exploratory query changes specific parameters of the DNS query structure - using a particular question type and carefully selected domain name format - to probe for functional limitations without triggering crashes. The query parameters are modified to be detectable yet safe
2Reliability
If an exploratory query is constructed to detect functional limitations, then the DNS server stability is improved, but the query construction complexity increases
Solution Approach 1:
The system introduces an intermediary exploratory query that acts as a mediator between the client and the DNS server. This intermediate query structure allows detection of server limitations without directly exposing the client to crash-inducing queries or requiring complex server-side modifications
3Reliability
If remedial actions are taken to avoid crashing queries, then the DNS server reliability is improved, but the response time for DNS resolution increases
Solution Approach 1:
The exploratory query and remedial actions are performed once during initialization or configuration. After the system adapts to the DNS server's capabilities by disabling problematic features, normal DNS resolution proceeds efficiently without repeated detection overhead, minimizing time loss
Data Source
AI summary
A system that determines if a DNS server suffers from a particular known functional limitation. During operation, the system sends an exploratory query to the DNS server, wherein the exploratory query is specially constructed so as to detect the existence of a functional limitation in the DNS server without causing the DNS server to fail. Next, the system receives an answer to the exploratory query from the DNS server. If the DNS server gives an incorrect response, the system can take actions as may be desired for the implementation. For example, the system may display a message identifying the functional limitation, or the system may establish a mode of operation where it avoids performing those types of DNS queries known to present a risk of crashing the particular Internet gateway.