175.78.168.0/21

Public

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

Network Address

175.78.168.0

Broadcast Address

175.78.175.255

Subnet Mask

255.255.248.0

Usable Hosts

2,046

First Usable IP

175.78.168.1

Last Usable IP

175.78.175.254

Total IPs

2,048

Prefix Length

/21

Network address — the base address of the block (175.78.168.0). All devices in this subnet share this prefix. Cannot be assigned to a host.

Broadcast address — packets sent to 175.78.175.255 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	175.78.168.0/21
Network Address	175.78.168.0
Broadcast Address	175.78.175.255
Subnet Mask	255.255.248.0
Wildcard Mask	0.0.7.255
Prefix Length	/21
IP Address Class	Class B
Total IP Addresses	2,048
Usable Host Addresses	2,046
First Usable IP	175.78.168.1
Last Usable IP	175.78.175.254
Network (Hex)	0xAF4EA800
Broadcast (Hex)	0xAF4EAFFF
Address Type	Public / Globally Routable

Binary Representation

Network Address

10101111.01001110 10101111.01001110.10101000.00000000

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 175.78.168.0/21 into 2 equal /22 subnets (1,022 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	175.78.168.0/22	175.78.168.0	175.78.168.1	175.78.171.254	175.78.171.255	1,022
2	175.78.172.0/22	175.78.172.0	175.78.172.1	175.78.175.254	175.78.175.255	1,022

Split 175.78.168.0/21 into 4 equal /23 subnets (510 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	175.78.168.0/23	175.78.168.0	175.78.168.1	175.78.169.254	175.78.169.255	510
2	175.78.170.0/23	175.78.170.0	175.78.170.1	175.78.171.254	175.78.171.255	510
3	175.78.172.0/23	175.78.172.0	175.78.172.1	175.78.173.254	175.78.173.255	510
4	175.78.174.0/23	175.78.174.0	175.78.174.1	175.78.175.254	175.78.175.255	510

Split 175.78.168.0/21 into 8 equal /24 subnets (254 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	175.78.168.0/24	175.78.168.0	175.78.168.1	175.78.168.254	175.78.168.255	254
2	175.78.169.0/24	175.78.169.0	175.78.169.1	175.78.169.254	175.78.169.255	254
3	175.78.170.0/24	175.78.170.0	175.78.170.1	175.78.170.254	175.78.170.255	254
4	175.78.171.0/24	175.78.171.0	175.78.171.1	175.78.171.254	175.78.171.255	254
5	175.78.172.0/24	175.78.172.0	175.78.172.1	175.78.172.254	175.78.172.255	254
6	175.78.173.0/24	175.78.173.0	175.78.173.1	175.78.173.254	175.78.173.255	254
7	175.78.174.0/24	175.78.174.0	175.78.174.1	175.78.174.254	175.78.174.255	254
8	175.78.175.0/24	175.78.175.0	175.78.175.1	175.78.175.254	175.78.175.255	254

Split 175.78.168.0/21 into 16 equal /25 subnets (126 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	175.78.168.0/25	175.78.168.0	175.78.168.1	175.78.168.126	175.78.168.127	126
2	175.78.168.128/25	175.78.168.128	175.78.168.129	175.78.168.254	175.78.168.255	126
3	175.78.169.0/25	175.78.169.0	175.78.169.1	175.78.169.126	175.78.169.127	126
4	175.78.169.128/25	175.78.169.128	175.78.169.129	175.78.169.254	175.78.169.255	126
5	175.78.170.0/25	175.78.170.0	175.78.170.1	175.78.170.126	175.78.170.127	126
6	175.78.170.128/25	175.78.170.128	175.78.170.129	175.78.170.254	175.78.170.255	126
7	175.78.171.0/25	175.78.171.0	175.78.171.1	175.78.171.126	175.78.171.127	126
8	175.78.171.128/25	175.78.171.128	175.78.171.129	175.78.171.254	175.78.171.255	126
9	175.78.172.0/25	175.78.172.0	175.78.172.1	175.78.172.126	175.78.172.127	126
10	175.78.172.128/25	175.78.172.128	175.78.172.129	175.78.172.254	175.78.172.255	126
11	175.78.173.0/25	175.78.173.0	175.78.173.1	175.78.173.126	175.78.173.127	126
12	175.78.173.128/25	175.78.173.128	175.78.173.129	175.78.173.254	175.78.173.255	126
13	175.78.174.0/25	175.78.174.0	175.78.174.1	175.78.174.126	175.78.174.127	126
14	175.78.174.128/25	175.78.174.128	175.78.174.129	175.78.174.254	175.78.174.255	126
15	175.78.175.0/25	175.78.175.0	175.78.175.1	175.78.175.126	175.78.175.127	126
16	175.78.175.128/25	175.78.175.128	175.78.175.129	175.78.175.254	175.78.175.255	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 175.78.160.0/20 Sibling /21 block 175.78.160.0/21

Adjacent Prefix Sizes

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