28.0.0.0/9

Public

Class A — /9 prefix — 8,388,606 usable hosts

Network Address

28.0.0.0

Broadcast Address

28.127.255.255

Subnet Mask

255.128.0.0

Usable Hosts

8,388,606

First Usable IP

28.0.0.1

Last Usable IP

28.127.255.254

Total IPs

8,388,608

Prefix Length

Network address — the base address of the block (28.0.0.0). All devices in this subnet share this prefix. Cannot be assigned to a host.

Broadcast address — packets sent to 28.127.255.255 are delivered to every device in the subnet. Also reserved — not assignable.

Usable hosts — the 8,388,606 addresses between those two that you can assign to servers, VMs, or interfaces.

Subnet mask — 255.128.0.0 is the dotted-decimal equivalent of /9. Older tools and Cisco configs use this format instead of CIDR slash notation.

Full Details

CIDR Notation	28.0.0.0/9
Network Address	28.0.0.0
Broadcast Address	28.127.255.255
Subnet Mask	255.128.0.0
Wildcard Mask	0.127.255.255
Prefix Length	/9
IP Address Class	Class A
Total IP Addresses	8,388,608
Usable Host Addresses	8,388,606
First Usable IP	28.0.0.1
Last Usable IP	28.127.255.254
Network (Hex)	0x1C000000
Broadcast (Hex)	0x1C7FFFFF
Address Type	Public / Globally Routable

Binary Representation

Network Address

00011100 00011100.00000000.00000000.00000000

Subnet Mask

11111111.10000000.00000000.00000000

The first 9 bits (1s in the mask) identify the network. The remaining 23 bits identify hosts within the network.

Split into Equal Subnets

Split 28.0.0.0/9 into 2 equal /10 subnets (4,194,302 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	28.0.0.0/10	28.0.0.0	28.0.0.1	28.63.255.254	28.63.255.255	4,194,302
2	28.64.0.0/10	28.64.0.0	28.64.0.1	28.127.255.254	28.127.255.255	4,194,302

Split 28.0.0.0/9 into 4 equal /11 subnets (2,097,150 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	28.0.0.0/11	28.0.0.0	28.0.0.1	28.31.255.254	28.31.255.255	2,097,150
2	28.32.0.0/11	28.32.0.0	28.32.0.1	28.63.255.254	28.63.255.255	2,097,150
3	28.64.0.0/11	28.64.0.0	28.64.0.1	28.95.255.254	28.95.255.255	2,097,150
4	28.96.0.0/11	28.96.0.0	28.96.0.1	28.127.255.254	28.127.255.255	2,097,150

Split 28.0.0.0/9 into 8 equal /12 subnets (1,048,574 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	28.0.0.0/12	28.0.0.0	28.0.0.1	28.15.255.254	28.15.255.255	1,048,574
2	28.16.0.0/12	28.16.0.0	28.16.0.1	28.31.255.254	28.31.255.255	1,048,574
3	28.32.0.0/12	28.32.0.0	28.32.0.1	28.47.255.254	28.47.255.255	1,048,574
4	28.48.0.0/12	28.48.0.0	28.48.0.1	28.63.255.254	28.63.255.255	1,048,574
5	28.64.0.0/12	28.64.0.0	28.64.0.1	28.79.255.254	28.79.255.255	1,048,574
6	28.80.0.0/12	28.80.0.0	28.80.0.1	28.95.255.254	28.95.255.255	1,048,574
7	28.96.0.0/12	28.96.0.0	28.96.0.1	28.111.255.254	28.111.255.255	1,048,574
8	28.112.0.0/12	28.112.0.0	28.112.0.1	28.127.255.254	28.127.255.255	1,048,574

Split 28.0.0.0/9 into 16 equal /13 subnets (524,286 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	28.0.0.0/13	28.0.0.0	28.0.0.1	28.7.255.254	28.7.255.255	524,286
2	28.8.0.0/13	28.8.0.0	28.8.0.1	28.15.255.254	28.15.255.255	524,286
3	28.16.0.0/13	28.16.0.0	28.16.0.1	28.23.255.254	28.23.255.255	524,286
4	28.24.0.0/13	28.24.0.0	28.24.0.1	28.31.255.254	28.31.255.255	524,286
5	28.32.0.0/13	28.32.0.0	28.32.0.1	28.39.255.254	28.39.255.255	524,286
6	28.40.0.0/13	28.40.0.0	28.40.0.1	28.47.255.254	28.47.255.255	524,286
7	28.48.0.0/13	28.48.0.0	28.48.0.1	28.55.255.254	28.55.255.255	524,286
8	28.56.0.0/13	28.56.0.0	28.56.0.1	28.63.255.254	28.63.255.255	524,286
9	28.64.0.0/13	28.64.0.0	28.64.0.1	28.71.255.254	28.71.255.255	524,286
10	28.72.0.0/13	28.72.0.0	28.72.0.1	28.79.255.254	28.79.255.255	524,286
11	28.80.0.0/13	28.80.0.0	28.80.0.1	28.87.255.254	28.87.255.255	524,286
12	28.88.0.0/13	28.88.0.0	28.88.0.1	28.95.255.254	28.95.255.255	524,286
13	28.96.0.0/13	28.96.0.0	28.96.0.1	28.103.255.254	28.103.255.255	524,286
14	28.104.0.0/13	28.104.0.0	28.104.0.1	28.111.255.254	28.111.255.255	524,286
15	28.112.0.0/13	28.112.0.0	28.112.0.1	28.119.255.254	28.119.255.255	524,286
16	28.120.0.0/13	28.120.0.0	28.120.0.1	28.127.255.254	28.127.255.255	524,286

/9 Subnet Reference

Total IPs 8,388,608

Usable Hosts 8,388,606

Subnet Mask 255.128.0.0

Wildcard 0.127.255.255

Full /9 reference →

Related Ranges

Parent /8 block 28.0.0.0/8 Sibling /9 block 28.128.0.0/9

Adjacent Prefix Sizes

/7 33,554,430 hosts /8 16,777,214 hosts /9 8,388,606 hosts /10 4,194,302 hosts /11 2,097,150 hosts