Top 50 Most Referenced RFCs:

2717 2119: Key words for use in RFCs to Indicate Requirement Levels
421 822: STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES
393 791: Internet Protocol
344 2434: Guidelines for Writing an IANA Considerations Section in RFCs
337 3261: SIP: Session Initiation Protocol
332 793: Transmission Control Protocol
276 2578: Structure of Management Information Version 2 (SMIv2)
271 1035: Domain names - implementation and specification
270 1034: Domain names - concepts and facilities
263 2579: Textual Conventions for SMIv2
251 1157: Simple Network Management Protocol (SNMP)
250 2026: The Internet Standards Process -- Revision 3
245 2580: Conformance Statements for SMIv2
228 2045: Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies
226 2460: Internet Protocol, Version 6 (IPv6) Specification
210 5226: Guidelines for Writing an IANA Considerations Section in RFCs
204 1213: Management Information Base for Network Management of TCP/IP-based internets:MIB-II
203 2616: Hypertext Transfer Protocol -- HTTP/1.1
201 2401: Security Architecture for the Internet Protocol
200 768: User Datagram Protocol
200 1700: Assigned Numbers
198 1155: Structure and identification of management information for TCP/IP-based internets
193 1122: Requirements for Internet Hosts - Communication Layers
192 5741: RFC Streams, Headers, and Boilerplates
189 1123: Requirements for Internet Hosts - Application and Support
188 3629: UTF-8, a transformation format of ISO 10646
187 1321: The MD5 Message-Digest Algorithm
182 3550: RTP: A Transport Protocol for Real-Time Applications
182 2104: HMAC: Keyed-Hashing for Message Authentication
179 3410: Introduction and Applicability Statements for Internet-Standard Management Framework
175 821: Simple Mail Transfer Protocol
171 3986: Uniform Resource Identifier (URI): Generic Syntax
171 2234: Augmented BNF for Syntax Specifications: ABNF
170 2205: Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification
168 1212: Concise MIB definitions
160 4301: Security Architecture for the Internet Protocol
156 2246: The TLS Protocol Version 1.0
152 1661: The Point-to-Point Protocol (PPP)
151 1112: Host extensions for IP multicasting
139 5234: Augmented BNF for Syntax Specifications: ABNF
138 2046: Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types
137 1905: Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)
136 792: Internet Control Message Protocol
134 2863: The Interfaces Group MIB
131 3209: RSVP-TE: Extensions to RSVP for LSP Tunnels
129 2409: The Internet Key Exchange (IKE)
129 2131: Dynamic Host Configuration Protocol
128 2396: Uniform Resource Identifiers (URI): Generic Syntax
127 3264: An Offer/Answer Model with Session Description Protocol (SDP)
124 4566: SDP: Session Description Protocol