Request for Comments (RFC)

Introduction

A Request for Comments (RFC) is a formal technical publication used to document Internet protocols, standards, technical methods, operational practices, research, policies, and other information relevant to the Internet. The RFC Series is an archival series dedicated to documenting Internet technical specifications, including standards documents and contributions from the Internet research and engineering community.

Although the name Request for Comments originated from an informal process for sharing technical ideas, an RFC is not simply a document asking for feedback. A published RFC can define a protocol, establish a Best Current Practice, document an experimental technology, describe research, or preserve historical information.

What Does RFC Stand For?

RFC stands for Request for Comments.

The first RFC was published in April 1969 as part of the effort to design and build what became the Internet. The RFC Series subsequently evolved into a permanent archival publication series for Internet technical specifications and related material.

The name remained even though the purpose of RFCs expanded significantly beyond its original role.

What Is the Purpose of an RFC?

RFCs provide a common technical reference for the Internet community.

An RFC may be used to:

• Define an Internet protocol or protocol extension.
• Specify technical requirements and procedures.
• Document an Internet Standard.
• Establish a Best Current Practice.
• Describe an experimental protocol or technology.
• Document Internet-related research.
• Record historical technical information.
• Define policies and procedures.
• Provide technical guidance to implementers and operators.

Therefore, the RFC Series is broader than an Internet standards repository. It provides a long-term technical record of Internet protocols, architecture, practices, research, and related activities.

RFC and Internet Standard Are Not the Same

One of the most important concepts to understand is that not every RFC is an Internet Standard.

RFC is a published technical document in the RFC Series.

Internet Standard is a specification that has achieved Internet Standard status through the applicable standards process.

An RFC can belong to several different categories or publication streams. Some RFCs define standards, while others document informational, experimental, historical, research, or operational material.

The IETF document stream is the stream through which Standards Track and Best Current Practice RFCs are published.

Who Produces RFCs?

The RFC Series includes documents from several publication streams.

IETF

The Internet Engineering Task Force (IETF) is the primary organization responsible for developing Internet standards.

The IETF document stream includes documents produced through the IETF standards process, including Standards Track and Best Current Practice RFCs.

IRTF

The Internet Research Task Force (IRTF) focuses on research related to Internet protocols, applications, architecture, and technology.

Research developed through IRTF activities can be published as RFCs without necessarily becoming Internet Standards.

IAB

The Internet Architecture Board (IAB) addresses broader architectural and technical matters affecting the Internet.

The IAB has its own document stream within the RFC Series.

Independent Submission Stream

Technical documents can enter the RFC Series through the Independent Submission Stream. These documents are outside the IETF, IAB, and IRTF document streams and are subject to their own review and approval process.

How Does an RFC Become Published?

Many RFCs begin as Internet-Drafts.

An Internet-Draft is a working document that can be discussed, reviewed, revised, and considered for publication. The process followed depends on the publication stream.

For IETF documents, technical development takes place through the IETF community and, where applicable, an IETF Working Group. The document goes through technical review, discussion, revision, and the appropriate approval process.

Once a document has been approved for publication, it proceeds through the RFC publication process. The RFC Editor is responsible for the operational implementation of the RFC Series, including editing, processing, and publication.

An Internet-Draft should therefore not be treated as equivalent to a published RFC.

What Happens After an RFC Is Published?

A published RFC becomes part of the permanent RFC Series archive.

RFCs are not normally modified after publication when technical changes are required. Instead, a later RFC can update or obsolete an earlier RFC.

An RFC may also have errata, which identify errors or issues discovered after publication.

When using an RFC as a technical reference, it is therefore important to determine whether:

• The RFC has been updated.
• The RFC has been obsoleted.
• The RFC updates another RFC.
• The RFC obsoletes another RFC.
• Relevant errata exist.
• A newer specification should be consulted.

This is especially important when implementing protocols because an older RFC may no longer represent the current specification.

RFC Status and Categories

RFCs can have different classifications depending on their purpose.

Proposed Standard

A Proposed Standard is a Standards Track specification that has entered the standards process and received the required technical review and community consideration.

It represents an important stage in the development of an Internet Standard.

Internet Standard

An Internet Standard represents the mature Standards Track status of a specification.

It has progressed through the applicable standards process and achieved the required level of community consensus, review, and implementation experience.

Best Current Practice

A Best Current Practice (BCP) RFC documents practices that are considered appropriate for the Internet community.

BCPs do not necessarily define network protocols. They may address operational practices, policies, procedures, or recommendations.

Informational

An Informational RFC provides information that is considered useful to the Internet community.

It may document technical information, explanations, research, historical material, or other information without defining an Internet Standard.

Experimental

An Experimental RFC documents a technology or approach intended for experimentation and evaluation.

Experimental specifications are generally not presented as established Internet Standards.

Historic

A Historic RFC documents a specification or technology that is no longer part of the active standards framework.

Historic RFCs remain useful for understanding the development of Internet technologies and standards.

How Are RFCs Numbered?

Each published RFC receives a unique number.

Examples include:

• RFC 791
• RFC 793
• RFC 1034
• RFC 1035
• RFC 8446
• RFC 9110

The number identifies the document within the RFC Series.

RFC numbers are assigned sequentially throughout the history of the series. The number itself does not indicate the technical importance, standards status, or quality of an RFC.

For example, a higher RFC number does not automatically mean that the document represents a higher-level standard than an RFC with a lower number.

The document’s status, publication stream, and relationship with other RFCs must be examined separately.

Examples of Important RFCs

RFC 791 defines Internet Protocol version 4 (IPv4).

RFC 8200 specifies Internet Protocol version 6 (IPv6).

RFC 1034 and RFC 1035 define fundamental aspects of the Domain Name System (DNS).

RFC 8446 specifies TLS 1.3, an important protocol for securing communications over networks.

RFC 9110 defines the semantics of HTTP.

These examples demonstrate the breadth of the RFC Series. RFCs can define fundamental networking protocols as well as security-related mechanisms and application-layer technologies.

RFCs, IETF, and RFC Editor

The relationship between the IETF, RFC Series, and RFC Editor should be clearly understood.

The IETF develops Internet standards and related technical specifications through an open community process.

The RFC Series provides the formal publication and archival record for these documents and other technical material.

The RFC Editor manages the publication and archival function of the RFC Series.

These terms therefore describe different things:

• IETF is an Internet standards-development organization and community.
• RFC Series is a collection of published technical documents.
• RFC Editor is responsible for the publication and archival function of the RFC Series.
• RFC is an individual published document within the RFC Series.

Understanding these distinctions prevents the common misconception that an RFC, IETF, and Internet Standard are interchangeable terms.

RFC vs Internet-Draft

An Internet-Draft is a working document.

An RFC is a published document in the RFC Series.

An Internet-Draft can be revised during development and may eventually become an RFC, but publication is not guaranteed.

Once an RFC is published, it becomes part of the permanent RFC Series archive. Technical changes are normally addressed through subsequent RFCs that update or obsolete the original document.

Therefore, when researching a protocol, it is important to distinguish between a working Internet-Draft and the final published RFC.

How to Read an RFC

RFCs can initially appear complex because they use a formal technical-document structure. A systematic approach makes them easier to understand.

Start by examining:

1. RFC number — identifies the document.
2. Title — identifies its subject.
3. Status — indicates its publication or standards classification.
4. Abstract — provides a concise description.
5. Introduction — explains the problem and context.
6. Technical sections — describe the protocol, architecture, requirements, or procedures.
7. Security Considerations — describes security implications.
8. IANA Considerations — identifies required actions involving IANA registries, where applicable.
9. References — identifies related specifications and supporting material.
10. RFC relationships — identifies documents that update or obsolete the RFC.

When studying an RFC, it is also useful to follow the references because a specification may depend on several other RFCs.

Why RFCs Matter

RFCs provide the Internet community with a common technical foundation.

They allow engineers, researchers, architects, developers, vendors, network operators, and cybersecurity professionals to refer to formally documented technical specifications rather than relying entirely on proprietary documentation or informal explanations.

The RFC Series is also an important historical record. It preserves the evolution of Internet protocols, standards, architecture, operational practices, and technical research.

For cybersecurity professionals, RFCs are particularly valuable because many security controls and network technologies depend on protocols defined or documented within the RFC Series.

Learning how to locate, interpret, and validate RFCs is therefore an important skill for anyone working with networking, cybersecurity, Internet architecture, or security engineering.

Conclusion

A Request for Comments (RFC) is a published technical document in the RFC Series that can define Internet protocols, document standards, establish Best Current Practices, describe experimental technologies, present research, or provide other technical information relevant to the Internet.

The RFC Series began during the early development of the ARPANET and evolved into a permanent technical archive. Importantly, not every RFC is an Internet Standard. RFCs can have different statuses and can originate through different publication streams.

The IETF, RFC Series, and RFC Editor also have distinct roles. The IETF develops Internet standards and related technical specifications, the RFC Series provides the formal publication and archival record, and the RFC Editor manages the publication process.

For networking and cybersecurity professionals, RFCs provide authoritative technical references for understanding the protocols, architectures, security mechanisms, and operational practices that form the foundation of Internet communication.

References

IAB – The RFC Series and RFC Editor, RFC 8729
Defines the RFC Series mission, publication streams, and roles and responsibilities associated with the RFC Editor.

IETF – The Internet Standards Process — Revision 3, RFC 2026
Defines the Internet Standards process and the framework for developing, reviewing, and advancing Internet specifications.