# Best current practice

A best current practice, abbreviated as BCP, is a de facto level of performance in engineering and information technology. It is more flexible than a standard, since techniques and tools are continually evolving. The Internet Engineering Task Force publishes Best Current Practice documents in a numbered document series. Each document in this series is paired with the currently valid Request for Comments (RFC) document. BCP was introduced in RFC-1818.
BCPs are document guidelines, processes, methods, and other matters not suitable for standardization. The Internet standards process itself is defined in a series of BCPs, as is the formal organizational structure of the IETF, Internet Engineering Steering Group, Internet Architecture Board, and other groups involved in that process. IETF's separate Standard Track (STD) document series defines the fully standardized network protocols of the Internet, such as the Internet Protocol, the Transmission Control Protocol, and the Domain Name System.
Each RFC number refers to a specific version of a document Standard Track, but the BCP number refers to the most recent revision of the document. Thus, citations often reference both the BCP number and the RFC number. Example citations for BCPs are: BCP 38, RFC 2827.

## Significant fields of application
### BCP related to IPv6

| BCP number | Title |
| BCP157 | IPv6 Address Assignment to End Sites |
| BCP177 | IPv6 Support Required for All IP-Capable Nodes |
| BCP198 | IPv6 Prefix Length Recommendation for Forwarding |

### BCP related to DNS

| BCP number | Title |
| BCP016 | Selection and Operation of Secondary DNS Servers |
| BCP017 | Use of DNS Aliases for Network Services |
| BCP020 | Classless IN-ADDR.ARPA delegation |
| BCP032 | Reserved Top Level DNS Names |
| BCP042 | Domain Name System (DNS) IANA Considerations |
| BCP049 | Delegation of IP6.ARPA |
| BCP052 | Management Guidelines & Operational Requirements for the Address and Routing Parameter Area Domain ("arpa") |
| BCP065 | Dynamic Delegation Discovery System (DDDS) Part Five: URI.ARPA Assignment Procedures |
| BCP080 | Delegation of E.F.F.3.IP6.ARPA |
| BCP091 | DNS IPv6 Transport Operational Guidelines |
| BCP109 | Deprecation of "ip6.int" |
| BCP123 | Observed DNS Resolution Misbehavior |
| BCP152 | DNS Proxy Implementation Guidelines |
| BCP155 | Nameservers for IPv4 and IPv6 Reverse Zones |
| BCP163 | Locally Served DNS Zones |

### BCP related to security

| BCP number | Title |
| BCP021 | Expectations for Computer Security Incident Response |
| BCP038 | Network Ingress Filtering: Defeating Denial of Service Attacks which employ IP Source Address Spoofing |
| BCP046 | Recommended Internet Service Provider Security Services and Procedures |
| BCP061 | Strong Security Requirements for Internet Engineering Task Force Standard Protocols |
| BCP072 | Guidelines for Writing RFC Text on Security Considerations |
| BCP106 | Randomness Requirements for Security |
| BCP136 | Secure Connectivity and Mobility Using Mobile IPv4 and IKEv2 Mobility and Multihoming (MOBIKE) |
| BCP140 | Preventing Use of Recursive Nameservers in Reflector Attacks |
| BCP188 | Pervasive Monitoring Is an Attack |
| BCP194 | BGP Operations and Security |
| BCP195 | Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) |
| BCP199 | DHCPv6-Shield: Protecting against Rogue DHCPv6 Servers |

### BCP related to globalization

| BCP number | Title |
| BCP047 | Tags for Identifying Languages (IETF language tag) |