Multi-Tier DNS Caching for Document Access Latency
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Solution Overview
Problem
Current web browsing experiences are hindered by slow document download speeds due to limited Internet bandwidth, inefficiencies in the HTTP protocol, and limitations of client-side caching, including cache size constraints and freshness issues, as well as the risk of accessing unavailable documents.
Innovation Solution
A system and method utilizing a DNS cache and DNS master for self-refreshing and prefetching, which processes hostname resolution requests to identify valid IP addresses, updates address records, and coordinates with a remote cache server to ensure document freshness and availability, leveraging a persistent connection and content difference generation to enhance caching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cache is established in the client computer to store downloaded files, then document download speed is improved for frequently accessed content, but the cache size is limited and cannot store a large number of documents
Solution Approach 1:
The patent transitions from single-dimensional client-side caching to multi-dimensional caching by introducing server-side caching as an additional layer. This allows the system to overcome client cache size limitations while maintaining fast access to frequently downloaded documents through the server cache that can store larger quantities of content.
Solution Approach 2:
The patent introduces a cache server as an intermediary between the document host and the client computer. This intermediary cache server handles storage and retrieval of downloaded documents, relieving the client cache from storing all documents while still providing fast access to frequently accessed content through coordinated caching between client and server.
2Loss of time
If the web browser cache is used to store documents, then access time for cached documents is reduced, but the browser cannot determine whether cached documents are fresh and may needlessly re-download them
Solution Approach 1:
The patent implements a feedback mechanism where the cache server communicates with both the document host and the client browser. The cache server receives freshness information from the document host and relays it to the client, enabling the client to determine whether cached documents are fresh without needing to re-download them, thus reducing unnecessary network traffic and improving access efficiency.
Solution Approach 2:
The cache server autonomously manages document freshness by automatically checking with document hosts and updating its own cache accordingly. This self-service approach eliminates the need for the client browser to manually verify document freshness, reducing the client's computational burden while ensuring accurate freshness information is available.
3Productivity
If conventional client-side caching is implemented, then frequently accessed static content is loaded faster, but the system cannot handle cases where documents are removed from the host or the host is temporarily out of service
Solution Approach 1:
The patent implements prior cushioning by having the cache server pre-fetch and store copies of documents before the client needs them. The cache server proactively downloads and caches documents from the host, creating a buffer that protects the client from host unavailability. When the host is temporarily out of service or documents are removed, the client can still access previously cached copies from the cache server.
Solution Approach 2:
The patent creates redundant copies of documents by storing them in both the client cache and the cache server. This copying strategy ensures that if the original host is unavailable or documents are removed, the client can retrieve document copies from the cache server, thereby improving document availability and system reliability.
Data Source
AI summary
The present invention is directed to a system and method of performing a lookup, self-refreshing and prefetching against a DNS provider that includes a DNS cache and a DNS master. The DNS cache includes a set of address records which are presumptively fresh and the DNS master includes another set of address records which may be updated if their respective IP addresses are not deemed fresh or identified for update based on other factors. A hostname resolution request is first processed by the DNS cache and then by the DNS master to identify a valid IP address for a hostname. If no valid IP address is found, the DNS master retrieves a new IP address for the hostname from a third-party DNS server and then updates the addresses records in the DNS cache and master with the new IP address. Entries in the DNS master are updated from time to time increasing the likelihood that fresh addresses are predominately present and to update the DNS cache.