{
  "patent_number": "US 6178160",
  "country": "US",
  "title": "How DNS Servers Route Web Traffic to the Least Busy Server",
  "original_title": "Load balancing of client connections across a network using server based algorithms",
  "summary": "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.",
  "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."
  ],
  "filed": "1997-12-23",
  "granted": "2001-01-23",
  "expires": "2017-12-23",
  "status": "expired",
  "holder": "Cisco Technology Inc",
  "holder_url": "https://patentbrief.org/company/cisco-technology-inc",
  "inventors": [
    {
      "name": "Derek W. Bolton",
      "url": "https://patentbrief.org/inventor/derek-w-bolton"
    },
    {
      "name": "Rajesh Agrawal",
      "url": "https://patentbrief.org/inventor/rajesh-agrawal"
    }
  ],
  "times_cited": 123,
  "tags": [
    "telecommunications",
    "software",
    "consumer_electronics"
  ],
  "abstract": "A plurality of web servers (16, 18, and 20) have a common host name, and their authoritative domain server (24 or 26) responds to requests from a local domain-name server (22) for the network address corresponding to their common host name by making an estimate of the performance costs of adding a further client to each of the web servers and then sending the local domain-name server (22) the network address of the server to which the addition of a further client will result in the least performance cost. The performance cost is defined as the difference in the average number of waiting clients, and it takes into account both the additional response time for existing clients and the projected response time for the prospective new client.",
  "url": "https://patentbrief.org/patent/us/6178160/load-balancing-of-client-connections-across-a-network-using-server-based-algorithms",
  "markdown_url": "https://patentbrief.org/patent/us/6178160/load-balancing-of-client-connections-across-a-network-using-server-based-algorithms/md",
  "google_patents_url": "https://patents.google.com/patent/US6178160",
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}