# How DNS Servers Route Web Traffic to the Least Busy Server > A method for balancing web traffic by having servers report their current workload to a DNS server, which then directs new users to the fastest available machine. - **Patent:** US 6178160 - **Original title:** Load balancing of client connections across a network using server based algorithms - **Owner:** Cisco Technology Inc - **Granted:** 2001 - **Status:** Public domain (expired) - **Times cited:** 123 - **Field:** telecommunications, software, consumer_electronics ## What it does This patent describes a system where multiple web servers share a single domain name (like www.example.com). Each server monitors its own performance by measuring how long it takes to respond to requests and how many clients are currently waiting. The servers send these performance metrics to a central DNS server. When a new user tries to visit the site, the DNS server uses this data to calculate which server is currently the least busy and sends the user to that specific machine's network address. ## What it does NOT cover - Does not cover load balancing performed by hardware appliances like dedicated load balancers sitting in front of servers. - Does not cover client-side selection where the user's browser decides which server to connect to. - Does not cover simple round-robin DNS where servers are chosen in a fixed sequence regardless of their actual performance. ## The clever bit The system shifts the intelligence of load balancing into the DNS lookup process itself, using real-time performance feedback from the servers to make routing decisions before the user even connects. ## Real-world examples 1. Early web server clusters 2. Global Server Load Balancing (GSLB) systems 3. Content Delivery Network (CDN) routing logic ## Why it matters This technology was essential for the early scaling of the internet. Before this, popular websites would crash if one server became overwhelmed. By using DNS to intelligently distribute traffic, companies could keep services online even when user demand spiked, laying the groundwork for modern cloud infrastructure. ## Frequently asked questions ### What does How DNS Servers Route Web Traffic to the Least Busy Server cover? A method for balancing web traffic by having servers report their current workload to a DNS server, which then directs new users to the fastest available machine. ### Who owns patent US 6178160? Cisco Technology Inc owns this patent, granted in 2001. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 6178160 cited by? This patent has been cited by 123 later patents that build on its ideas. ### What problem does this patent solve? This technology was essential for the early scaling of the internet. Before this, popular websites would crash if one server became overwhelmed. By using DNS to intelligently distribute traffic, companies could keep services online even when user demand spiked, laying the groundwork for modern cloud infrastructure. ### What does this patent NOT cover? Does not cover load balancing performed by hardware appliances like dedicated load balancers sitting in front of servers. **Full plain-English explainer:** https://patentbrief.org/patent/us/6178160/load-balancing-of-client-connections-across-a-network-using-server-based-algorithms **Original patent:** https://patents.google.com/patent/US6178160 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Load Balancers Route Web Traffic Based on Specific Content](https://patentbrief.org/patent/us/5774660/world-wide-web-server-with-delayed-resource-binding-for-resource-based-load-balancing-on-a-distributed-resource-multi-node-network) — A method for web servers to route user requests to specific machines based on which files they store, rather than just blindly balancing traffic across all servers. - [How Amazon Optimizes Website Loading Speeds by Managing Domain Requests](https://patentbrief.org/patent/us/7930393/amazon-cloudfront-cdn) — A system that tests different ways to distribute website resources across multiple domains to find the fastest way to load a webpage for users. - [How Servers Share an IP Address for High Availability](https://patentbrief.org/patent/us/9571603/redundancy-network-protocol-system) — Cisco's 2017 patent describes a system where multiple servers can share a single virtual IP address to ensure an application stays online even if one server fails. - [How CDNs Use Client-Side Code to Speed Up Web Downloads](https://patentbrief.org/patent/us/9544394/aws-cloudtrail) — Amazon's patent on using client-side code like JavaScript to dynamically rewrite website links so they point directly to the fastest content delivery server, bypassing traditional DNS routing bottlenecks. - [How Amazon Delivers Content Faster Using Local Servers](https://patentbrief.org/patent/us/9332078/facebook-memories) — Amazon's 2016 patent describes a system for breaking down digital content into smaller pieces and storing them on servers located near users to speed up downloads and reduce network traffic.