IPRangeExplorer

166.252.128.0/21

Public

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

Network Address
166.252.128.0
Broadcast Address
166.252.135.255
Subnet Mask
255.255.248.0
Usable Hosts
2,046
First Usable IP
166.252.128.1
Last Usable IP
166.252.135.254
Total IPs
2,048
Prefix Length
/21

Network address — the base address of the block (166.252.128.0). All devices in this subnet share this prefix. Cannot be assigned to a host.

Broadcast address — packets sent to 166.252.135.255 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 166.252.128.0/21
Network Address 166.252.128.0
Broadcast Address 166.252.135.255
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 166.252.128.1
Last Usable IP 166.252.135.254
Network (Hex) 0xA6FC8000
Broadcast (Hex) 0xA6FC87FF
Address Type Public / Globally Routable

Binary Representation

Network Address
10100110.11111100 10100110.11111100.10000000.00000000
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 166.252.128.0/21 into 2 equal /22 subnets (1,022 usable hosts each).

# CIDR Network First Usable Last Usable Broadcast Hosts
1 166.252.128.0/22 166.252.128.0 166.252.128.1 166.252.131.254 166.252.131.255 1,022
2 166.252.132.0/22 166.252.132.0 166.252.132.1 166.252.135.254 166.252.135.255 1,022

/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 166.252.128.0/20 Sibling /21 block 166.252.136.0/21

Adjacent Prefix Sizes

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

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