Ch003 H2: new 17k chars (핵심 개념 4 깊게 — 5층 봉투/IPv4·v6·CIDR/TCP 3-way·4-way·재전송·혼잡제어/UDP 5사용처/HTTP 메서드5+멱등성/상태코드5묶음+401vs403+502vs504/헤더 7가족+보안헤더/DNS 레코드7종+TTL+resolver chain+dig +trace/TLS 1.3 1-RTT/인증서 체인+openssl/curl -v 9줄 풀이/자경단 4기둥/함정5+FAQ5/추신19)

Author: GoGoComputer