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.
Original patent title: “Load balancing of client connections across a network using server based algorithms”
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. Granted to Cisco Technology Inc in 2001 with 12 claims and 123 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
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.
The gap
What does this patent 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.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
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.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Early web server clusters
Global Server Load Balancing (GSLB) systems
Content Delivery Network (CDN) routing logic
Why it matters
The bigger picture
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.
Filed
December 23, 1997
Granted
January 23, 2001
Market context
Who's building on this
Companies in this space
Cisco remains a major player in networking hardware, but this logic is now standard practice across major cloud providers like Amazon Web Services (AWS), Google Cloud, and Microsoft Azure. These companies have evolved these concepts into highly sophisticated, automated traffic management systems.
Market impact
This patent helped formalize the practice of intelligent traffic steering, which is now a fundamental requirement for any large-scale web service. It moved the industry away from static, manual server management toward the dynamic, automated scaling that powers today's internet.
Claim 1 — Plain English
What this patent covers
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.
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.
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.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Strong
Citation count
40/40
Highly cited
Claim breadth
8/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
20/20
Major company or institution
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$53K – $168K
Midpoint $105K · expired or expiring · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Claim text not yet imported for this patent
The original legal language
Original claims
12 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Bolton, D. W., & Agrawal, R. (2001). How DNS Servers Route Web Traffic to the Least Busy Server (U.S. Patent No. 6,178,160). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/6178160/load-balancing-of-client-connections-across-a-network-using-server-based-algorithms
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
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.
Same assignee
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