Networking / AV-IT
Subnet / CIDR Notation
01 — Definition
The logical subdivision of an IP network, written in CIDR. /24 = 254 usable hosts (the standard), /23 = 510, /22 = 1022, /21 = 2046. A /16 climbs to 65,534 hosts: far too wide for events, and an open door to ARP broadcast storms — rule it out in AV. And two devices on different subnets will not talk to each other without a router.
02 — In the field
Two devices on different subnets cannot see each other directly. The classic mistake: one device on 192.168.1.x/24, another on 192.168.2.x/24 — different subnets, no direct communication. Keep all production AV on a single /24 per service type.
04 — Sources
- RFC 1918 §3 — blocs privés 10/8, 172.16/12, 192.168/16