10.3.96.0/21

Private (RFC 1918) RFC 1918

Class A — /21 prefix — 2,046 usable hosts

Network Address

10.3.96.0

Broadcast Address

10.3.103.255

Subnet Mask

255.255.248.0

Usable Hosts

2,046

First Usable IP

10.3.96.1

Last Usable IP

10.3.103.254

Total IPs

2,048

Prefix Length

/21

Network address — the base address of the block (10.3.96.0). All devices in this subnet share this prefix. Cannot be assigned to a host.

Broadcast address — packets sent to 10.3.103.255 are delivered to every device in the subnet. Also reserved — not assignable.

Usable hosts — the 2,046 addresses between those two that you can assign to servers, VMs, or interfaces.

Subnet mask — 255.255.248.0 is the dotted-decimal equivalent of /21. Older tools and Cisco configs use this format instead of CIDR slash notation.

Full Details

CIDR Notation	10.3.96.0/21
Network Address	10.3.96.0
Broadcast Address	10.3.103.255
Subnet Mask	255.255.248.0
Wildcard Mask	0.0.7.255
Prefix Length	/21
IP Address Class	Class A
Total IP Addresses	2,048
Usable Host Addresses	2,046
First Usable IP	10.3.96.1
Last Usable IP	10.3.103.254
Network (Hex)	0x0A036000
Broadcast (Hex)	0x0A0367FF
Governing RFC	RFC 1918
Address Type	Private (RFC 1918)

Binary Representation

Network Address

00001010.00000011 00001010.00000011.01100000.00000000

Subnet Mask

11111111.11111111.11111000.00000000

The first 21 bits (1s in the mask) identify the network. The remaining 11 bits identify hosts within the network.

Split into Equal Subnets

Split 10.3.96.0/21 into 2 equal /22 subnets (1,022 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	10.3.96.0/22	10.3.96.0	10.3.96.1	10.3.99.254	10.3.99.255	1,022
2	10.3.100.0/22	10.3.100.0	10.3.100.1	10.3.103.254	10.3.103.255	1,022

Split 10.3.96.0/21 into 4 equal /23 subnets (510 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	10.3.96.0/23	10.3.96.0	10.3.96.1	10.3.97.254	10.3.97.255	510
2	10.3.98.0/23	10.3.98.0	10.3.98.1	10.3.99.254	10.3.99.255	510
3	10.3.100.0/23	10.3.100.0	10.3.100.1	10.3.101.254	10.3.101.255	510
4	10.3.102.0/23	10.3.102.0	10.3.102.1	10.3.103.254	10.3.103.255	510

Split 10.3.96.0/21 into 8 equal /24 subnets (254 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	10.3.96.0/24	10.3.96.0	10.3.96.1	10.3.96.254	10.3.96.255	254
2	10.3.97.0/24	10.3.97.0	10.3.97.1	10.3.97.254	10.3.97.255	254
3	10.3.98.0/24	10.3.98.0	10.3.98.1	10.3.98.254	10.3.98.255	254
4	10.3.99.0/24	10.3.99.0	10.3.99.1	10.3.99.254	10.3.99.255	254
5	10.3.100.0/24	10.3.100.0	10.3.100.1	10.3.100.254	10.3.100.255	254
6	10.3.101.0/24	10.3.101.0	10.3.101.1	10.3.101.254	10.3.101.255	254
7	10.3.102.0/24	10.3.102.0	10.3.102.1	10.3.102.254	10.3.102.255	254
8	10.3.103.0/24	10.3.103.0	10.3.103.1	10.3.103.254	10.3.103.255	254

Split 10.3.96.0/21 into 16 equal /25 subnets (126 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	10.3.96.0/25	10.3.96.0	10.3.96.1	10.3.96.126	10.3.96.127	126
2	10.3.96.128/25	10.3.96.128	10.3.96.129	10.3.96.254	10.3.96.255	126
3	10.3.97.0/25	10.3.97.0	10.3.97.1	10.3.97.126	10.3.97.127	126
4	10.3.97.128/25	10.3.97.128	10.3.97.129	10.3.97.254	10.3.97.255	126
5	10.3.98.0/25	10.3.98.0	10.3.98.1	10.3.98.126	10.3.98.127	126
6	10.3.98.128/25	10.3.98.128	10.3.98.129	10.3.98.254	10.3.98.255	126
7	10.3.99.0/25	10.3.99.0	10.3.99.1	10.3.99.126	10.3.99.127	126
8	10.3.99.128/25	10.3.99.128	10.3.99.129	10.3.99.254	10.3.99.255	126
9	10.3.100.0/25	10.3.100.0	10.3.100.1	10.3.100.126	10.3.100.127	126
10	10.3.100.128/25	10.3.100.128	10.3.100.129	10.3.100.254	10.3.100.255	126
11	10.3.101.0/25	10.3.101.0	10.3.101.1	10.3.101.126	10.3.101.127	126
12	10.3.101.128/25	10.3.101.128	10.3.101.129	10.3.101.254	10.3.101.255	126
13	10.3.102.0/25	10.3.102.0	10.3.102.1	10.3.102.126	10.3.102.127	126
14	10.3.102.128/25	10.3.102.128	10.3.102.129	10.3.102.254	10.3.102.255	126
15	10.3.103.0/25	10.3.103.0	10.3.103.1	10.3.103.126	10.3.103.127	126
16	10.3.103.128/25	10.3.103.128	10.3.103.129	10.3.103.254	10.3.103.255	126

/21 Subnet Reference

Total IPs 2,048

Usable Hosts 2,046

Subnet Mask 255.255.248.0

Wildcard 0.0.7.255

Full /21 reference →

Related Ranges

Parent /20 block 10.3.96.0/20 Sibling /21 block 10.3.104.0/21

Adjacent Prefix Sizes

/19 8,190 hosts /20 4,094 hosts /21 2,046 hosts /22 1,022 hosts /23 510 hosts