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: 12.128.3.0/31
Addresses: 2 (2¹)
First IP: 12.128.3.0 (0.3.128.12.in-addr.arpa)
Last IP: 12.128.3.1 (1.3.128.12.in-addr.arpa)

/8 Operated By: AT&T Bell Laboratories

Related Networks

12.0.0.0/8
11.0.0.0/8
13.0.0.0/8
12.128.3.0/30
12.128.3.0/32
12.128.3.1/32

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