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Leonard Kleinrock
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Leonard Kleinrock

UCLA scientist whose lab sent the first message over the ARPANET

13 June 1934 United States Verified by our editors
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Age
92 yrs
Birthday in 219 days
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2
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Leonard Kleinrock is an American computer scientist at UCLA who developed the mathematical theory of packet networks. On 29 October 1969 his laboratory sent the first message over the ARPANET, the forerunner of the internet, to Stanford Research Institute.

Biography

Education

Kleinrock grew up in Manhattan, built a crystal radio from a comic-book plan as a boy and studied electrical engineering at City College of New York at night. He earned his PhD at MIT in 1962.

Theory of networks

His doctoral work applied queueing theory to networks in which messages are broken into pieces and sent through switches, showing such networks could be efficient. It provided mathematical support for packet switching.

The first message

At UCLA his lab hosted the first ARPANET node. On 29 October 1969 his student Charley Kline tried to log in to the SRI computer; the system crashed after “LO” of “LOGIN” — the first message on the network.

Later work

Kleinrock has trained many networking researchers, co-founded companies, and received the National Medal of Science in 2007. He predicted in 1969 that computer networks would become a utility like electricity.

Timeline

  1. 1934

    Born in New York City, United States

  2. 1962

    PhD from MIT

  3. 1963

    Joins UCLA

  4. 1969

    First ARPANET node and message

  5. 1976

    Queueing Systems volumes

  6. 2001

    Draper Prize

  7. 2007

    National Medal of Science

  8. 2012

    Internet Hall of Fame

Notable works

  • 1964

    Communication Nets Book

  • 1975

    Queueing Systems Book

Awards and honours

  • Marconi Prize

    1986

  • Charles Stark Draper Prize

    2001

  • National Medal of Science

    2007

Did you know?

  1. 1

    The room where the first message was sent, UCLA Boelter Hall 3420, is now a museum.

  2. 2

    Vint Cerf and Jon Postel worked in his lab.

  3. 3

    He shared the 2001 Draper Prize with Cerf, Kahn and Roberts.

Connections

Related people

Also born on 13 June

Frequently asked

Who is Leonard Kleinrock?

Leonard Kleinrock is an American computer scientist at UCLA who developed the mathematical theory of packet networks. On 29 October 1969 his laboratory sent the first message over the ARPANET, the forerunner of the internet, to Stanford Research Institute.

How old is Leonard Kleinrock?

Leonard Kleinrock is 92 years old, born on 13 June 1934 in New York City, United States.

Where is Leonard Kleinrock from?

Leonard Kleinrock was born in New York City, United States.

What is Leonard Kleinrock known for?

Leonard Kleinrock is best known for Queueing theory for packet networks; first ARPANET message (1969).

What awards has Leonard Kleinrock received?

Notable honours include Marconi Prize (1986), Charles Stark Draper Prize (2001), National Medal of Science (2007).

References

  1. Leonard Kleinrock — Wikipedia. Wikipedia. Retrieved 4 November 2026.
  2. Leonard Kleinrock — Britannica. Encyclopaedia Britannica. Retrieved 4 November 2026.
  3. Official website. www.lk.cs.ucla.edu. Retrieved 4 November 2026.
  4. Leonard Kleinrock (Q32338) — structured data. Wikidata. Retrieved 4 November 2026.

Includes material from the Wikipedia article “Leonard Kleinrock”, licensed under CC BY-SA 4.0. That text is available under the same licence. Learn more

External links

Official website Website Wikipedia
Filed under ARPANETInternetUCLA Computer ScientistProfessor

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“Leonard Kleinrock.” TrackFame, last updated 5 November 2026. https://trackfame.com/person/leonard-kleinrock

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