| 1035 | Domain names - implementation and specificationP. Mockapetris | Internet Standard | November 1987 |
| 1191 | Path MTU discoveryJ. Mogul, S. Deering | Draft Standard | November 1990 |
| 1939 | Post Office Protocol - Version 3J. Myers, M. Rose | Internet Standard | May 1996 |
| 1981 | Path MTU Discovery for IP version 6J. McCann, S. Deering, J. Mogul · obsoleted by RFC 8201 | Draft Standard | August 1996 |
| 2119 | Key words for use in RFCs to Indicate Requirement LevelsS. Bradner | Best Current Practice | March 1997 |
| 2246 | The TLS Protocol Version 1.0T. Dierks, C. Allen · obsoleted by RFC 4346 | Historic | January 1999 |
| 2401 | Security Architecture for the Internet ProtocolS. Kent, R. Atkinson · obsoleted by RFC 4301 | Proposed Standard | November 1998 |
| 2402 | IP Authentication HeaderS. Kent, R. Atkinson · obsoleted by RFC 4302, RFC 4305 | Proposed Standard | November 1998 |
| 2406 | IP Encapsulating Security Payload (ESP)S. Kent, R. Atkinson · obsoleted by RFC 4303, RFC 4305 | Proposed Standard | November 1998 |
| 2409 | The Internet Key Exchange (IKE)D. Harkins, D. Carrel · obsoleted by RFC 4306 | Historic | November 1998 |
| 2521 | ICMP Security Failures MessagesP. Karn, W. Simpson | Experimental | March 1999 |
| 2960 | Stream Control Transmission ProtocolR. Stewart, Q. Xie, K. Morneault, C. Sharp, H. Schwarzbauer, T. Taylor, I. Rytina, M. Kalla, L. Zhang, V. Paxson · obsoleted by RFC 4960 | Proposed Standard | October 2000 |
| 2988 | Computing TCP's Retransmission TimerV. Paxson, M. Allman · obsoleted by RFC 6298 | Proposed Standard | November 2000 |
| 3261 | SIP: Session Initiation ProtocolJ. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, E. Schooler | Proposed Standard | July 2002 |
| 3501 | INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1M. Crispin · obsoleted by RFC 9051 | Proposed Standard | March 2003 |
| 4306 | Internet Key Exchange (IKEv2) ProtocolC. Kaufman, Ed. · obsoleted by RFC 5996 | Proposed Standard | December 2005 |
| 4346 | The Transport Layer Security (TLS) Protocol Version 1.1T. Dierks, E. Rescorla · obsoleted by RFC 5246 | Historic | April 2006 |