ICANN's foundational policy, Appendix K, meticulously reserves critical domain names like 'icann', 'iana', and 'www' across all TLDs, alongside single/two-character labels and key TLD strings. This analysis reveals how these reservations, established in 2001, prevent conflicts, protect critical infrastructure, and underpin DNS security and stability. Understanding this 'namespace zoning' is crucial for developers navigating domain registration and internet governance.