Lesson 3 of 412 min

DHCP (Dynamic Host Configuration Protocol) and just-enough subnetting

Scopes, reservations, options. /24, /23, /22 — what you actually need to know.

Network switch with a bundle of ethernet cables — Photo by Brett Sayles on Pexels

DHCP hands out IP (Internet Protocol) addresses, subnet masks, gateway, and DNS (Domain Name System) servers. A 'scope' is the range it can hand out. A 'reservation' pins a specific MAC (Media Access Control) to a specific IP.

Most small offices live in a /24 (254 hosts). Big offices need /23 or larger. Memorize: /24=256, /23=512, /22=1024.

Diagram · Small-office network

If two devices have the same IP, one DHCP scope is misconfigured or there are two DHCP servers fighting.

Key takeaways

▸DHCP delivers IP + mask + gateway + DNS
▸Reservations beat static IPs for printers/servers
▸Conflicts = two servers handing out the same range

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