More detailsNeighboring subnets, wildcard mask, hex, reverse DNS, and binary breakdown
Neighboring /28 subnets
- Wildcard mask
- Used in Cisco ACLs and OSPF
- CIDR notation
- IP in hexadecimal
- IP as 32-bit integer
- Reverse DNS (PTR)
- Host bits / subnet bits
Binary breakdown
IP address
11000000.10101000.00000001.00000000Subnet mask
11111111.11111111.11111111.11110000Network
11000000.10101000.00000001.00000000Broadcast
11000000.10101000.00000001.00001111Quick facts for /28
- Subnet mask: 255.255.255.240
- Wildcard: 0.0.0.15
- Usable hosts: 14
- Total addresses: 16
/28 reference guideBit split, overview, sizing tables, notable networks, and FAQ
Binary bit split
11111111·11111111·11111111·11110000
Network bits (28)Host bits (4)
- Network bits
- 28
- Host bits
- 4
- Subnet mask
- 255.255.255.240
- Wildcard mask
- 0.0.0.15
- Total addresses
- 16
- Usable hosts
- 14
- Hosts formula
- 2^4 − 2
- /24 relationship
- 16 fit per /24
Overview
A /28 block contains 16 addresses with 14 usable. A popular size for small server clusters, cloud management subnets, and VPN concentrator networks where only a small number of hosts are needed.
Common use cases
- Small server cluster or rack network
- Cloud management or bastion subnet
- VPN concentrator or firewall segment
- Network printer or IoT device group
Subnet sizing reference
Notable /28 networks
10.0.0.0/28.0–.15 (14 usable hosts)192.168.1.0/28.0–.15 example
Frequently asked questions
Common questions about /28 networks, subnet masks, and use cases.