What's a UUID?

This report analyzes UUID-like labels observed in DNS traffic collected from Farsight's Security Information Exchange and DNSDB: it explains RFC4122 UUID types (1, 3, 4, 5), shows Python examples for generating and inspecting UUIDs, and presents empirical results from a 10M-record sample showing that ~99.5% of observed UUIDs are RFC4122 Type 4 (random) with examples of domains and distribution across second-level domains.