Internet Assigned Numbers Authority IP Version Numbers Last Updated 2021-01-28 Note In the Internet Protocol (IP) [RFC791][RFC8200] there is a field to identify the version of the internetwork general protocol. This field is 4 bits in size. Available Formats [IMG] XML [IMG] HTML [IMG] Plain text Registry included below * IP Version Numbers IP Version Numbers Registration Procedure(s) Standards Action Reference [RFC2780] Available Formats [IMG] CSV Decimal Keyword Version Reference 0-1 Reserved [Jon_Postel][RFC4928] 2-3 Unassigned [Jon_Postel] 4 IP Internet Protocol [RFC791][Jon_Postel] 5 Reserved (Historic) [RFC1819][SC589H] 6 IPv6 Internet Protocol version 6 [RFC8200] 7 Reserved (Historic) [RFC1475][RFC6814] 8 Reserved (Historic) [RFC1621][SC589H] 9 Reserved (Historic) [RFC1347][SC589H] 10-14 Unassigned [Jon_Postel] 15 Reserved [Jon_Postel] Contact Information ID Name Contact URI Last Updated [Jon_Postel] Jon Postel mailto:postel&isi.edu Licensing Terms