python: ipaddress package output not consistent with CIDR website

Question

I am converting some CIDR using python ipaddress package like:

import ipaddress
net4 = ipaddress.ip_network(u'10.120.160.0/19')
for x in net4.hosts():
    print(x)

The first_ip output from the above code is 10.120.160.1 , while the last_ip from the above code is 10.120.191.254

However, if I use the website: http://www.ipaddressguide.com/cidr to do the conversion: the first_ip becomes 10.120.160.0 while the last_ip becomes 10.120.191.255

Does anyone know why the results are different and which one is correct? Thanks!

Answer 1

The last address will be the subnet's broadcast address, so you can't give it to a host, and the first is the network's address itself, which is also not assigned to hosts. So both sources are correct, they just tell you different things: the python routine gives you IPs suitable for hosts, while the web page gives you all IPs in the range, including network and broadcast.