Internet Links

The Internet Corporation of Assigned Names and Numbers, ICANN is the starting point for all names and numbers, though it delegates a lot of detail to IANA, regional IP assigners, and Domain Registrars.
The Internet Assigned Numbers Authority, IANA maintains port assignments, protocol numbers, a database of TLDs, etc.

Each of the Regional IP assigners maintains it’s own whois look-up. They all have simple searches off their home pages, but also have an advanced query page

Region	Assigner	Query Page
Americas	American Registry for Internet Numbers ARIN	ARIN Whois
Europe	Réseaus IP Européens Network Coodrination Centre RIPE	RIPE Whois
Asia Pacific	Asia Pacific Network Information Centre APNIC	APNIC Whois

The ultimate source for DNS is still the InterNic which also runs a whois search |
Protocols are defined in RFCs which are published by the Internet Engineering Task Force IETF, which maintains a searchable RFC Repository