Akamai Technologies The Network Time Protocol (NTP) and Network Time Security (NTS) documents define a number of assigned number registries, collectively called the NTP registries. Some registries have wrong values, some registries do not follow current common practice, and some are just right. For the sake of completeness, this document reviews all NTP and NTS registries, and makes updates where necessary. This document updates RFC 5905, RFC 5906, RFC 8573, RFC 7822, and RFC 7821.