The Internet Assigned Number Authority (IANA) hosts the registry for special numbers for many protocols and many Internet Engineering Task Force (IETF) standards.

BGP: https://www.iana.org/protocols#:~:text=Border%20Gateway%20Protocol%20(BGP)%20Parameters
DNS: https://www.iana.org/protocols#:~:text=Domain%20Name%20System%20(DNS)%20Parameters
DNSSEC: https://www.iana.org/protocols#:~:text=Domain%20Name%20System%20Security%20(DNSSEC)%20Algorithm%20Numbers
IP Addresses: https://www.iana.org/numbers
IPv4 Address Space: https://www.iana.org/protocols#:~:text=Internet%20Protocol%20version%204%20(IPv4)%20Address%20Space
IPv4 Protocol: https://www.iana.org/protocols#:~:text=Internet%20Protocol%20Version%204%20(IPv4)%20Parameters
IPv6 Protocol: https://www.iana.org/protocols#:~:text=Internet%20Protocol%20Version%206%20(IPv6)%20Parameters
MIME: https://www.iana.org/protocols#:~:text=Multipurpose%20Internet%20Mail%20Extensions%20(MIME)%20and%20Media%20Types
TCP: https://www.iana.org/protocols#:~:text=Transmission%20Control%20Protocol%20(TCP)%20Parameters
TLS: https://www.iana.org/protocols#:~:text=Transport%20Layer%20Security%20(TLS)