Hostname Tagging for CDN Address Blacklisting
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Solution Overview
Problem
In content delivery networks (CDNs), conventional systems fail to effectively handle unsatisfactory IP addresses by not providing alternative solutions when initial addresses are unreachable or perform poorly, leading to repeated unsatisfactory connections.
Innovation Solution
The solution involves modifying hostnames with tagged prefixes to blacklist unsatisfactory IP addresses, allowing the rendezvous system to exclude these addresses during subsequent name-resolution requests, thereby ensuring clients connect to optimal servers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DNS resolution is used without tracking bad addresses, then the system is simple and easy to operate, but clients repeatedly connect to unsatisfactory servers leading to poor reliability
Solution Approach 1:
The system performs preliminary actions by modifying the hostname to include a tagged prefix that encodes information about bad IP addresses before the DNS resolution process. This allows the rendezvous system to proactively exclude known bad addresses from the resolution process, preventing clients from connecting to unsatisfactory servers in the first place, thereby improving connection reliability without requiring complex real-time tracking mechanisms
Solution Approach 2:
The tagged prefix in the hostname acts as an intermediary that carries information about bad addresses through the DNS resolution process. Instead of requiring direct communication between clients and the rendezvous system to track bad addresses, the tagged prefix mediates this information transfer, allowing the system to improve reliability while maintaining operational simplicity
2Reliability
If the system tracks and excludes bad IP addresses, then connection reliability improves, but the hostname structure and resolution process become more complex
Solution Approach 1:
The system changes the parameter of the hostname by adding a tagged prefix that encodes bad address information. This parameter change allows the hostname to carry additional information without requiring a complete restructuring of the DNS system, improving reliability while maintaining ease of operation through familiar DNS resolution processes
Solution Approach 2:
The tagged prefix adds another dimension to the hostname structure, allowing it to encode bad address information alongside the original domain name. This dimensional addition enables the system to track and exclude bad addresses without complicating the basic DNS operation, as the extra information layer can be processed transparently by the resolution system
3Productivity
If alternative server selection is implemented when initial addresses fail, then connection success rate improves, but the name-resolution process becomes slower
Solution Approach 1:
The system performs preliminary action by pre-encoding information about bad addresses in the tagged prefix before DNS resolution begins. This allows the rendezvous system to quickly filter out known bad addresses during the resolution process itself, rather than requiring clients to retry multiple times after connections fail, thereby improving connection success rate without significant time loss
Solution Approach 2:
The tagged prefix provides feedback information about bad addresses to the rendezvous system during the name-resolution process. This feedback mechanism allows the system to make informed decisions about server selection upfront, improving connection success rate while minimizing resolution time by avoiding iterative retry cycles
Data Source
AI summary
A computer-implemented method, in a content delivery (CD) network. The method includes: receiving a request regarding a first hostname including at least one tag and an encoding of the at least one address; removing the tag and the encoding of the address to form a second hostname; resolving the second hostname to obtain a set of one or more addresses, wherein the set does not include the at least one address; and returning the address set. On a client, the method includes: making a request for resolution of a first hostname; receiving one or more addresses; attempting to connect to at least one of the addresses; generating a modified hostname including at least one tag and an encoding of the at least one address; and requesting resolution of the modified hostname.