/22 Subnet Mask: 255.255.252.0
A /22 IPv4 subnet uses mask 255.255.252.0. It spans four consecutive /24 ranges, contains 1,024 total addresses and provides 1,022 traditional usable host addresses. The third-octet block size is 4 and the wildcard mask is 0.0.3.255.
/22 quick reference
| Prefix | /22 |
|---|---|
| Subnet / wildcard mask | 255.255.252.0 · 0.0.3.255 |
| Total / traditional usable | 1,024 · 1,022 |
| Host bits | 10 |
| Third-octet increment | 4 |
Worked example: 192.168.8.0/22
The third mask octet is 252, so 256 - 252 = 4. Valid third-octet boundaries are 0, 4, 8, 12 and continuing multiples of four. Because 8 is aligned, 192.168.8.0 is a valid /22 network:
| Role | Address |
|---|---|
| Network | 192.168.8.0 |
| First usable | 192.168.8.1 |
| Last usable | 192.168.11.254 |
| Broadcast | 192.168.11.255 |
| Next /22 | 192.168.12.0/22 |
Why a /22 crosses four /24s
The range covers third-octet values 8, 9, 10 and 11. Those are four blocks of 256 addresses, producing 4 × 256 = 1,024. The network address is the first address of the first /24; the directed broadcast is the final address of the fourth.
If the supplied address were 192.168.10.50/22, it would still belong to 192.168.8.0/22 because 10 falls within the aligned 8–11 block. Rounding the third octet down to the nearest multiple of four finds the network boundary.
Use /22 as an address block, not automatically one VLAN
A /22 can represent a routed summary or an allocation that is later divided into smaller subnets. Placing more than a thousand devices in one Layer-2 broadcast domain is usually a design decision that deserves careful review. Security boundaries, failure domains, DHCP scope, broadcast traffic and operational ownership may justify several smaller VLANs even when a /22 summary is advertised upstream.
The wildcard mask 0.0.3.255 matches all addresses in the aligned /22. For example, a Cisco ACL using 192.168.8.0 0.0.3.255 covers 192.168.8.0 through 192.168.11.255. Verify that broad range before deploying the rule.
Frequently asked questions
What is the subnet mask for /22?
The /22 subnet mask is 255.255.252.0.
How many usable hosts are in a /22?
A /22 contains 1,024 total IPv4 addresses and 1,022 traditional usable host addresses.
What is the wildcard mask for /22?
The wildcard mask is 0.0.3.255.
What third-octet values does 192.168.8.0/22 cover?
It covers 192.168.8.0 through 192.168.11.255; usable hosts run from 192.168.8.1 through 192.168.11.254.
Primary sources
- RFC 1878: Variable Length Subnet Table for IPv4
- Cisco: understand host and subnet quantities
- Cisco IOS: wildcard masks in access lists
Port registrations describe assigned names, not a guarantee about the process actually listening on a device. Confirm the local process and configuration before changing a firewall.
Related guides
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