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: 209.128.0.0/21
Addresses: 2048 (2¹¹)
First IP: 209.128.0.0 (0.0.128.209.in-addr.arpa)
Last IP: 209.128.7.255 (255.7.128.209.in-addr.arpa)

/8 Operated By: ARIN

Related Networks

209.0.0.0/8
208.0.0.0/8
210.0.0.0/8
209.128.0.0/20
209.128.0.0/32
209.128.7.255/32

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