Router DNS TTL Modification for Network Usage Estimation
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Solution Overview
Problem
Estimating and limiting the usage time of network applications across multiple devices and locations is impractical and expensive when done locally on each device, as it requires complex and costly methods.
Innovation Solution
A system that centrally modifies TTL values in DNS responses at a router, allowing for the estimation of usage time by counting DNS queries, and enforces time limits by blocking applications when a predefined query count is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If usage time is measured locally on each device, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a router as an intermediary device that centralizes the usage monitoring function. Instead of each device measuring its own usage, the router intercepts and counts DNS queries to estimate usage time. This transfers the measurement complexity from multiple end devices to a single centralized router, reducing overall system complexity while maintaining measurement capability.
Solution Approach 2:
The system leverages the existing DNS query mechanism that devices already perform for normal internet operation. By counting these existing DNS queries rather than implementing separate measurement protocols, the system achieves usage monitoring without adding extra communication overhead or complexity to individual devices.
2Measurement precision
If usage time is measured locally on each device, then measurement precision is improved, but implementation cost increases
Solution Approach 1:
The patent combines the usage monitoring function with the existing router infrastructure. By integrating usage estimation into the router's DNS interception capability rather than implementing separate monitoring software on each device, the system eliminates the need for multiple independent measurement systems, thereby reducing overall implementation cost.
Solution Approach 2:
The router performs multiple functions: it acts as both a network gateway (handling DNS queries for internet access) and a usage monitoring device (counting DNS queries to estimate usage time). This multi-functionality eliminates the need for dedicated monitoring hardware or software on end devices, reducing implementation costs.
3Ease of operation
If TTL values are modified centrally at router, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The patent modifies the TTL parameter in DNS response packets as a mechanism to control and track usage. By changing this existing DNS parameter to a fixed value, the system creates a standardized way to measure usage duration that works automatically with the DNS protocol, simplifying the operation of usage limiting while adding only minimal processing logic to the router.
Data Source
AI summary
A system and method to estimate and to limit usage time of network applications by a centrally located router is provided. The router first modifies the Domain Name System (DNS) protocol's Time To Live (TTL) values to a fix value, then it counts the number of DNS queries for an application. Number of queries multiplied by the fixed TTL value gives estimated duration of the application.