A /28 has 16 addresses, 14 usable, mask 255.255.255.240. It’s the smallest subnet AWS and Azure let you create, and because AWS reserves five addresses per subnet, a /28 there leaves only 11. On-premises, /28s suit small DMZs or management networks. Blocks start every 16 addresses: .0, .16, .32 and so on, so 10.0.0.37/28 belongs to 10.0.0.32/28.
Facts
- Prefix
- /28
- Subnet mask
- 255.255.255.240
- Wildcard mask
- 0.0.0.15
- Binary mask
- 11111111.11111111.11111111.11110000
- Total addresses
- 16
- Usable hosts
- 14
- Example range
- 192.168.1.0/28: 192.168.1.0 – 192.168.1.15
- Typical use
- Small segments; the smallest subnet AWS allows.
Try it
Try: , ,
- CIDR block
- 192.168.1.0/28
- IP range
- 192.168.1.0 – 192.168.1.15
- Addresses
- 16
- Usable hosts
- 14
- Subnet mask
- 255.255.255.240
- Wildcard mask
- 0.0.0.15
Frequently asked questions
How many hosts are in a /28?
A /28 has 16 addresses. Subtracting the network and broadcast addresses leaves 14 usable hosts.
What is the subnet mask for /28?
/28 is 255.255.255.240 (wildcard mask 0.0.0.15). In binary that’s 28 ones followed by 4 zeros.