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Paul Mockapetris

Summary

Paul Mockapetris is the American computer scientist who designed the Domain Name System (DNS), the Internet's directory of names, at USC's Information Sciences Institute in 1983. He published it as RFC 882 and RFC 883 that November, wrote the first DNS server, Jeeves, and in November 1987 published RFC 1034 and RFC 1035, still the core DNS standard. He later chaired the IETF from 1994 to 1996 and was inducted into the Internet Hall of Fame in 2012.

Web Building Encyclopedia · People · Last reviewed October 22, 2026 · 8 min read

Who Paul Mockapetris is

Paul V. Mockapetris is the American computer scientist who designed the Domain Name System (DNS), the Internet‘s directory that turns names such as example.com into the numeric addresses computers use. He did the work in 1983 at the University of Southern California’s Information Sciences Institute (ISI).12

The Internet Hall of Fame, which inducted him in 2012, says he “expanded the Internet beyond its academic origins” with that invention.1 The Association for Computing Machinery (ACM) credits him with designing DNS, publishing its specification in 1983 and building the first DNS server, a program called Jeeves.2

He later managed networking research at ARPA, chaired the Internet Engineering Task Force from 1994 to 1996 and held senior roles at several networking companies. As of August 2020, ACM described him as chief scientist at ThreatSTOP, a network security company in Carlsbad, California.13

Education and early work

The IEEE History Center’s ETHW gives his birth as November 18, 1948, in Boston, Massachusetts.4 He earned two bachelor’s degrees at the Massachusetts Institute of Technology, in physics and in electrical engineering, and ETHW dates them to 1971.45

As an MIT student he worked on a multiprocessor operating system for the Architecture Machine Group, on virtual machine operating systems for IBM and on simulation work at Draper Labs, according to the same biography.4

He then earned a PhD in information and computer science at the University of California, Irvine, which ETHW dates to 1982.4 At Irvine he worked on Dave Farber’s Distributed Computer System, a research project that built an early ring-shaped local area network and an operating system to run across it.46 The Internet Hall of Fame describes this as distributed systems and network work that came before commercial Ethernet and Token Ring.1

Mockapetris joined ISI in 1978.5 Before DNS, ISI says, he developed the first SMTP email server there. SMTP (Simple Mail Transfer Protocol) is the standard that Internet mail servers still use to pass messages to each other.57

Designing DNS, 1983

In the early 1980s every computer on the network learned every other computer’s name from one shared file, HOSTS.TXT, kept by the Network Information Center at SRI (SRI-NIC).8 USC’s account of the period says the file was edited every two weeks and was growing too large and too often out of date.9

Jon Postel, his ISI colleague, asked him to create a distributed index of the Internet.79 In a 2020 ACM interview, Mockapetris said Postel wanted a compromise among several competing proposals to replace HOSTS.TXT, and that most of the design came from his own experience building distributed systems.3

He described the main challenge as building in “as much functionality as possible using a simple set of features.”3 His 1988 paper with Kevin Dunlap lists the base requirements: hold at least everything in HOSTS.TXT, let the data be maintained in a distributed way, avoid size limits, work across many kinds of networks and perform acceptably.8

According to USC, the system was first tested on June 23, 1983.9 Mockapetris published the design in November 1983 as two RFCs, the numbered documents in which Internet protocols are written down:

  • RFC 882, “Domain Names: Concepts and Facilities.” It argued that the central host table was reaching the limit of what could be managed and proposed a distributed, consistent name space with local caching.10
  • RFC 883, “Domain Names: Implementation and Specification.” It warned that its message formats were preliminary and should not yet be used for real implementations.11

Sources differ on how to share the credit. The Internet Hall of Fame and ACM name Mockapetris as the inventor of DNS, and a 2003 USC article says he invented it as part of his collaboration with Postel.129 ISI’s 2003 announcement credits the DNS protocol to Mockapetris and its architecture to Postel.5 A 2006 USC article says Postel and Mockapetris invented it together at ISI, after Postel asked him to implement and develop the protocols.7 ACM says Mockapetris wrote the specification alone, and RFC 882 and RFC 883 list him as sole author.21011 ACM and ISI both credit him with the first implementation.25

Jeeves, the root servers and the 1987 standard

A specification on paper needed working software. ACM says Mockapetris wrote the first DNS server, Jeeves, and deployed it on the first root servers, the machines at the top of the naming tree, which made DNS operational.2 ISI says that by 1986 his implementation was running on all of the Internet’s root name servers.5 ThreatSTOP’s biography of him adds that he operated the original root servers for all Internet names.12

Other software soon joined it. The 1988 paper reports that the root was then served by seven redundant name servers: three TOPS-20 machines running Jeeves and four UNIX machines running BIND, the Berkeley Internet Name Domain server.8 The University of California, Berkeley began installing machines that relied only on DNS in the spring of 1985.8

Mockapetris kept revising the design as it was used:

  • RFC 973, January 1986. It recorded changes to RFC 882 and RFC 883, suggested operating guidelines and discussed problems seen in the running system.13
  • RFC 1034 and RFC 1035, November 1987. These replaced RFCs 882, 883 and 973.1415 RFC 1034 explains that the system had evolved from the RFC 882 and RFC 883 design based on experience with several implementations.14 Together the two documents form STD 13, the Internet Standard for domain names.16
  • RFC 1101, April 1989. It updated RFC 1034 and RFC 1035 with a way to store network names and other data types in DNS.17

The 1988 paper measured the change. In 1987 HOSTS.TXT held about 5,500 names, while more than 20,000 could be found through DNS.8 About 300 domains had been delegated by February 1987 and more than 650 by March 1988.8 Delegated means handed to another organization to run.

The DNS entry in this encyclopedia covers how the system works today, from root servers to record types and DNSSEC.

ARPA, the IETF and industry

From 1990 to 1993, Mockapetris was program manager for networking at ARPA, the US Defense Department’s research agency.518 ACM SIGCOMM says he fostered international use of multimedia conferencing, multicast and quality of service there.18 The Internet Hall of Fame adds gigabit and optical networking projects.1 He also chaired the Research Working Group of the US Federal Networking Council.5

He chaired the Internet Engineering Task Force (IETF), the body that writes most Internet standards, from 1994 to 1996. He followed Phillip Gross, chair from 1986 to 1994, and was followed by Fred Baker, chair from 1996 to 2001.19 He served on the Internet Architecture Board over the same years.18 At ISI he also directed the High Performance Computing and Communications Division.520

In 1995 he left academia to become employee number two at @Home, a company that brought Internet service to homes over cable modems.5 He later held leadership roles at Software.com (later Openwave), which made email software, and at Fiberlane and Siara, which built networking hardware; the Hall of Fame notes that Fiberlane became part of Cisco and Siara part of Redback Networks.14

In 1999 he joined Nominum, a company focused on DNS and IP addressing software.5 By 2003 he was its chairman and chief scientist.9 That year ISI also brought him back for six months as a visiting scholar at its Postel Center for Experimental Networking, to work on future DNS-based technologies.57

In 2013 he was named among the chairs of ICANN‘s strategy panels.21 He chaired the Strategy Panel on Identifier Technology Innovation, which was asked to produce a technology roadmap for DNS and other identifiers.22 Vint Cerf was among the other panel chairs.21

On December 15, 2015, ThreatSTOP announced him as its chief scientist, a new role guiding products and research into DNS-based security. The release also listed him as a Nominum board member.23 As of 2020 he also sat on the board of Farsight Security, another DNS-based security company.6

Honors

The table lists the main honors named in primary sources.

YearHonorSource
2003IEEE Internet AwardISI; IEEE History Center524
2004ACM Fellow, for contributions to the Internet including domain and email protocolsACM2
2005ACM SIGCOMM Award, for foundational work designing, developing and deploying DNSACM SIGCOMM18
2006Elected to the US National Academy of EngineeringUSC; ISI725
2006ACM SIGCOMM Test of Time Paper Award, for the 1988 paper with Kevin DunlapACM; ACM SIGCOMM326
2012Internet Hall of Fame, inducted as an InnovatorInternet Society27
2019ACM Software System Award, with a $35,000 prizeACM28

The National Academy of Engineering announced its 2006 class on February 10 of that year. Its citation honored him “for contributions to the Internet, including pioneering and standardizing the Domain Name System.”7 ISI’s history notes that he and Danny Cohen were elected that year largely for their work at ISI.25 He has also received a Distinguished Alumnus award from UC Irvine.5

The Internet Hall of Fame’s first class of 33 people was honored on April 23, 2012, in Geneva, at the Internet Society’s Global INET conference.27 The Hall of Fame has since listed him as an advisory board member and a 2022 emeritus advisor.1

ACM announced the 2019 Software System Award on May 20, 2020. It said Mockapetris designed and built the query protocol, a server and the initial root servers in 1983, and that DNS still uses the core parts he introduced.28 ISI’s John Heidemann, a DNS researcher, said the basic protocol Mockapetris set out is still in place.20

Looking back on the design

In the 2020 ACM interview, Mockapetris compared his work to designing the basement and first two floors of a building with simple materials while expecting it to become a skyscraper.3

He named one thing he would do differently: “I probably should have created a third document explaining the design choices.”3 He said such a document could have guided later extensions toward a more coherent DNS.3

His 1988 paper had already drawn lessons from the first years of use. Among them: caching works even across very different systems but should also cache negative answers, and it is often harder to remove a feature from a system than to add one.8

His recent work turns DNS toward security. He told ACM that putting threat blocking into routers and DNS servers protects network devices that have little security of their own.3

Timeline

  1. ACM names Mockapetris the winner of its 2019 Software System Award for DNS28
  2. ThreatSTOP announces Mockapetris as its chief scientist23
  3. ICANN names him among the chairs of its new strategy panels21
  4. Inducted into the Internet Hall of Fame as an Innovator in Geneva27
  5. Elected to the US National Academy of Engineering7
  6. Receives the ACM SIGCOMM Award for his work on DNS18
  7. Named an ACM Fellow2
  8. Receives the IEEE Internet Award5
  9. Joins Nominum, a DNS and IP addressing software company5
  10. Leaves academia to become employee number two at @Home5
  11. Becomes chair of the IETF, serving until 199619
  12. Publishes RFC 1034 and RFC 1035, the core DNS standard14
  13. Publishes the first DNS specifications, RFC 882 and RFC 88310
  14. DNS is first tested at USC's Information Sciences Institute9
  15. Joins USC's Information Sciences Institute5

What it means for your website

Every website address depends on the system Mockapetris designed. When a visitor types your domain name, DNS finds the server that holds your site, and the rules it follows still come from his 1987 documents, RFC 1034 and RFC 1035.141516

  • Your domain is one branch of his tree. RFC 1034 lets each part of the name space be handed to a different organization to run. Your domain registrar records which name servers answer for your domain, and those servers hold your records.14
  • The basic record types are decades old. A records (addresses), CNAME records (aliases), MX records (mail servers) and TXT records were all defined in RFC 1035 in 1987, so older guides to them still apply.15 Our DNS glossary entry explains each in a sentence.
  • Answers are cached by design. RFC 882 built local caching into DNS from the start.10 RFC 1034 advises lowering a record’s time to live before a planned change, so old copies expire quickly, then raising it again afterward.14 Do this before you move hosts or builders.
  • Email runs through DNS too. RFC 1035 defined the MX record that tells other servers where to deliver your mail.15 If you change DNS providers, copy your MX records first. Our page on websites and email covers the related SPF, DKIM and DMARC records.
  • DNS can also be a security layer. Mockapetris argues that blocking known threats in DNS servers protects devices that cannot protect themselves.3 Some business routers and DNS services offer this kind of filtering; ask your IT provider whether your office network uses it.

For a plain-language start on how names, registrars and hosting fit together, see domains 101.

See also

References

  1. Paul Mockapetris. Internet Hall of Fame. accessed October 22, 2026.
  2. Paul Mockapetris: ACM award recipient. Association for Computing Machinery (ACM). accessed October 22, 2026.
  3. People of ACM: Paul Mockapetris. Association for Computing Machinery (ACM). 2020-08-25. accessed October 22, 2026.
  4. Paul V. Mockapetris. Engineering and Technology History Wiki (ETHW), IEEE History Center. accessed October 22, 2026.
  5. ISI Names Dr. Paul Mockapetris Visiting Scholar. USC Information Sciences Institute. 2003-03-27. accessed October 22, 2026.
  6. Alumni Spotlight: Paul Mockapetris Receives ACM Software System Award for Developing the DNS. Shani Murray, Donald Bren School of Information and Computer Sciences, UC Irvine. 2020. accessed October 22, 2026.
  7. Two ISI alumni elected to NAE. USC Viterbi School of Engineering. 2006-03-20. accessed October 22, 2026.
  8. Development of the Domain Name System. Paul V. Mockapetris and Kevin J. Dunlap, Proceedings of ACM SIGCOMM '88, pages 123 to 133 (copy hosted by Princeton University). 1988. accessed October 22, 2026.
  9. ISI Marks 20th Anniversary of Domain Name System. USC Viterbi School of Engineering. 2003-06-26. accessed October 22, 2026.
  10. RFC 882: Domain Names, Concepts and Facilities. P. Mockapetris, USC Information Sciences Institute, RFC Editor. 1983-11. accessed October 22, 2026.
  11. RFC 883: Domain Names, Implementation and Specification. P. Mockapetris, USC Information Sciences Institute, RFC Editor. 1983-11. accessed October 22, 2026.
  12. Paul Mockapetris. ThreatSTOP. accessed October 22, 2026.
  13. RFC 973: Domain System Changes and Observations. P. Mockapetris, USC Information Sciences Institute, RFC Editor. 1986-01. accessed October 22, 2026.
  14. RFC 1034: Domain Names, Concepts and Facilities. P. Mockapetris, USC Information Sciences Institute, RFC Editor. 1987-11. accessed October 22, 2026.
  15. RFC 1035: Domain Names, Implementation and Specification. P. Mockapetris, USC Information Sciences Institute, RFC Editor. 1987-11. accessed October 22, 2026.
  16. STD 13. RFC Editor. accessed October 22, 2026.
  17. RFC 1101: DNS Encoding of Network Names and Other Types. P. Mockapetris, USC Information Sciences Institute, RFC Editor. 1989-04. accessed October 22, 2026.
  18. Paul V. Mockapetris wins 2005 ACM SIGCOMM Award. ACM SIGCOMM. 2005. accessed October 22, 2026.
  19. IESG past members. Internet Engineering Task Force (IETF). accessed October 22, 2026.
  20. Paul Mockapetris receives Software System Award. Joanna Maniti, USC Information Sciences Institute. 2020-08-27. accessed October 22, 2026.
  21. ICANN Strategy Panels: Chair Biography Links. ICANN. 2013-07-15. accessed October 22, 2026.
  22. Identifier Technology Innovation. ICANN Strategy Panels, ICANN. accessed October 22, 2026.
  23. DNS Inventor Paul Mockapetris Sets Sights on Cybersecurity. ThreatSTOP press release, via Firmenpresse. 2015-12-15. accessed October 22, 2026.
  24. IEEE Internet Award. Engineering and Technology History Wiki (ETHW), IEEE History Center. accessed October 22, 2026.
  25. The Internet Era. USC Information Sciences Institute. accessed October 22, 2026.
  26. ACM SIGCOMM Test of Time Paper Award. ACM SIGCOMM. accessed October 22, 2026.
  27. Internet Hall of Fame Inductees Honored at Historic First Annual Awards Ceremony in Geneva, Switzerland. Internet Society. 2012-04-23. accessed October 22, 2026.
  28. ACM Honors Computing Innovators for Advances in Research, Education and Industry. Association for Computing Machinery (ACM). 2020-05-20. accessed October 22, 2026.

Web Building Encyclopedia. First published October 22, 2026. Last reviewed October 22, 2026. Every fact on this page is linked to a source we opened. Spotted an error? Write to [email protected].