IPv4 Subnet Calculator

This calculator and tool allows you to type an IP address in and get information on a particular subnet. Enter an IP or range in CIDR notation.

Network: 4.0.0.21/32
Addresses: 1 (2⁰)
First IP: 4.0.0.21 (21.0.0.4.in-addr.arpa)
Last IP: 4.0.0.21 (21.0.0.4.in-addr.arpa)

Owned By: Level 3
/8 Operated By: ARIN

Related Networks

4.0.0.0/8
3.0.0.0/8
5.0.0.0/8
4.0.0.20/31

You can also use some of the other examples such as:

0.0.0.0/0
1.0.0.0/8
127.0.0.1
30.0.0.0/8
192.168.0.0/16