DNS, DHCP, and Name Resolution Questions

How names and addresses are served and kept working on a network. DNS: resolution flow (stub, recursive, authoritative, root/TLD referrals), host-side resolver configuration and why one machine or process resolves differently from another, record types and their pitfalls (including apex aliasing, MX, SRV and CAA use), zones, delegation and glue, caching, TTL and negative caching, split-horizon and private zones, reverse DNS, zone transfers (AXFR/IXFR, TSIG), DNSSEC and key rollover, resolver and authoritative fleet design, forwarding versus running recursion, encrypted DNS (DoH/DoT), truncation, TCP fallback and EDNS, DNS-layer attacks (cache poisoning, amplification, spoofed-source floods), DNS health from the user's point of view, and DNS changes, mail and registrar migrations and outages. DHCP: address assignment and leases, scopes and sizing, reservations, relay across VLANs including relay agent information (option 82), redundancy and failover, and rogue or exhausted-scope failures. Includes diagnosing resolution failures that masquerade as wider outages. Excludes the layered network fault-isolation method and general packet capture, Active Directory-integrated DNS on domain controllers, DNS-based service registries for microservices, load-balancing algorithm design and global traffic steering, incident-command process and SLO or error-budget design, and generic scripting or infrastructure-as-code tooling.